Update: We've added to the Samsung Galaxy S6 comparison at the bottom of this review, now we've finished our full review.
After years of mocking rivals for producing larger and larger screens, and sticking to its pocket-sized principles, Apple finally caved in this year, introducing not one larger-screened model, but two: the iPhone 6 with a 4.7in screen, and the iPhone 6 Plus with a 5.5in screen. It's quite a climbdown on Apple's part, but it had to do it: another year with only a 4in screen on its flagship phone and consumers would have voted with their feet, steadily trickling away to Samsung, HTC, and LG's larger-screened alternatives. See also: the 17 best smartphones of 2015.
In reality, Apple shouldn't have been so frightened to make the move, because neither of the new phones feels out of place in today's large-screen-obsessed smartphone market.
Apple iPhone 6: size and design
The iPhone 6, the smaller of the two phones, is the one that works best. Apple has gone back to rounded edges this time around, moving away from the dead straight sides of the previous four handsets (the edges of the glass on the front are slightly curved, too), and this works to create an impression that the phone is smaller than it is. It's comfortable to hold, doesn't feel too slippery in your hand – an accusation we could level at the iPhone 5 and iPhone 5s – and the 4.7in screen size feels just right.
If you've been worried about the jump in screen size from the 5s' 4in diagonal, you'll wonder what all the fuss was about once you get your hands on the iPhone 6. Yes, it's taller, wider and a touch heavier than its predecessor at 129g, but it's far from unwieldy, even when slotted into one of Apple's wraparound leather cases. In fact, the extra size means it's easier to use in some respects: typing accurately, for instance, becomes far easier thanks to the larger onscreen keys, and using the iPhone 6 as a satnav in the car is a far more pleasurable experience with the extra screen real estate.
The sheer thinness of the handset makes it pretty comfortable to hold, too. It measures only 7.1mm from front to back, 0.5mm slimmer than the iPhone 5s, and in the current smartphone market it's out-skinnied only by the skeletal Huawei Ascend P7(6.5mm).
Apple has put some thought into helping those who just don't get on with the size of the new phone: a light double-tap on the home button slides the whole screen down, allowing one-handed access to icons, buttons and address menus located in the top half of the screen. However, after several months of use, we don't really think it's needed. We can count the number of times we've deliberately engaged it on the fingers of one hand; in fact, after a while we simply forgot the iPhone had grown, and got on with life. We certainly wouldn't want to go back to the tiny iPhone 5s.
Aside from the size, there are a couple of other physical changes to take note of. The power button has moved from the top edge of the device to the side, simultaneously making it easier to reach and also a little easier to hit by mistake when picking up the phone. The volume buttons are long and slim instead of circular, which makes them a touch easier to find without looking, and there's now a single speaker grille on the bottom edge of the phone, where the iPhone 5s had a pair.
The oddest change to the design, however, is the protruding camera lens, which sticks out around a millimetre from the rear of the case. In everyday use, you probably won't notice it: it doesn't stick out far enough to catch on the lip of your pocket when sliding it in and out, you won't feel it when holding the phone and if you put your iPhone 6 in a case the point is moot anyway.
The only major concern is for those who prefer to enjoy their iPhone in the metal; with the lens bearing the brunt of the impact every time you slap the phone down on a flat, hard surface, we have concerns about how long it will last.
Apple iPhone 6: display
The sleek industrial design is accompanied by a swathe of upgrades to the hardware inside, but it's the screen that makes the biggest impact. Along with the increase in size, Apple has boosted the iPhone 6's resolution to 750 x 1,344, giving a pixel density of 327ppi (a mere fraction higher than the iPhone 5s' 326ppi), and it looks pin-sharp.
Brightness, contrast and colour accuracy are also all exemplary, with the iPhone reaching a maximum brightness of 585cd/m2, gaining an eye-popping 1,423:1 contrast ratio, a highly impressive colour accuracy rating with a Delta E of 1.74, and sRGB coverage of 95%. That contrast ratio is particularly impressive, and a significant improvement on the 5s' 972:1, lending onscreen images a little more depth and dynamism.
There's one small caveat to all this, however. On our sample model, we noticed a dim strip around 5mm thick running along the top of the screen. Initially we didn't spot it thanks to the clutter of menus, but when we dropped into the full-screen reading view on the Kindle app, it became immediately apparent. It's a shame, since aside from this, the iPhone 6's display is as good as we've seen on any smartphone.
Apple iPhone 6: performance
Behind the screen, the changes are even more dramatic. The iPhone 6, along with its big brother, sports a new dual-core A8 CPU, with 1GB of RAM, upgraded graphics and an improved M8 motion coprocessor (that's the low-power chip designed to save energy by monitoring the phone's sensors). There are models with 16GB, 64GB and 128GB of storage (but, oddly, no 32GB model), and Apple has added a barometer to the phone's line-up of sensors, for more accurate reporting of relative altitude and atmospheric pressure.
Moving on to the slightly more demanding Peacekeeper benchmark, we saw a score of 2,533 – way in front of every other smartphone we've tested. It's the same story in Geekbench 3, with a single-core score of 1,631 that wipes the floor with everything else, and a multi-core score that's only marginally beaten by the quad-core Qualcomm hardware in the Samsung Galaxy S5. Given that the iPhone 6 has half the number of cores as the Samsung, it's still a seriously impressive showing. And as for the GFXBench T-Rex HD gaming test, there's simply no competition: the only phone capable of beating the iPhone 6's 51fps is the iPhone 6 Plus, which averaged a silky smooth 53fps despite its higher-resolution Full HD screen.
Apple iPhone 6: battery life
Perhaps more importantly, battery life is also excellent. The new, more efficient 20nm CPU clearly helps here: playing a 720p video with flight mode on and the screen set to a brightness of 120cd/m2, the battery depleted at 7.5% per hour, while streaming audio continuously from our SoundCloud account over 3G with the screen off reduced capacity at 1.7% per hour. The former result isn't all that special: plenty of other phones we've seen perform at this level or better, notably the Sony Xperia Z2(5.6%), Samsung Galaxy S5 (5.2%) and the HTC One M8(6.5%). But none of these handsets can match the iPhone 6's results in the 3G streaming test, a figure that points at highly impressive standby performance.
Even in continuous use, though, the iPhone 6 is one of the longest-lasting phones out there. In one morning, the battery dropped from 100% to only 84% during four hours of heavy testing. In that time, we streamed a podcast for 1hr 32mins, downloaded and installed the Facebook and Twitter apps, ran the Peacekeeper benchmark twice and the SunSpider browser test once, received a short phone call, and replied to a handful of texts. During this period the display was on constantly. This is a phone that will easily get you through a day and a half of moderate to light use and, if you're careful, two full days is not beyond it.
As with most smartphones, this does depend on your usage, and one thing that hits battery life hard is gaming. In the GFXBench battery test, which loops a 3D OpenGL animation for around half an hour and then estimates total runtime, the iPhone 6 achieved a total runtime of 2hrs 29mins. That's an improvement over the iPhone 5s' 1hr 52mins (impressive given how many more frames the phone is rendering), but it still indicates that graphics-heavy gaming will lead to a significantly shorter time span between charging sessions.
Elsewhere, Apple has added NFC to the iPhone 6, which is used solely for the Apple Pay touch credit-card payment system – it isn't used for Bluetooth pairing. It's an interesting development that could eventually see you paying for your morning coffee by tapping your phone to a card reader, and uses the phone's Touch ID fingerprint reader in conjunction with your credit-card details to provide increased security. Since the system won't arrive in the UK until early 2015 at the earliest, however, we don't think it's anything to get worked up about. You'll still need your plastic for the foreseeable future.
We're much more interested in the move, finally, to 802.11ac from 802.11n. Connection speed is a maximum of 433Mbits/sec, so it's single stream, and at close range using the FileBrowser app to transfer a large movie file from shared NAS storage to the iPhone, we saw roughly twice the speed from the iPhone 6 over the 5s, with transfer rates hovering between 7.5MB/sec and 8.5MB/sec over 802.11ac compared to between 6MB/sec and 7MB/sec for the 5s over 802.11n.
Apple iPhone 6: cameras
On paper, the camera isn't a huge upgrade from last year's flagship. You get an 8-megapixel 1/3in backside-illuminated CMOS sensor with 1.5 micron photo sites, and an aperture of f/2.2 – the same as the 5s. It's accompanied by Apple's True Tone flash so indoor shots don't look horribly washed out and ghostly.
The difference is that the camera now sports a number of phase-detect autofocus pixels on the surface of the sensor, in a similar fashion to the Galaxy S5 and many enthusiast and high-end SLR cameras, enabling much faster autofocus.
In practice, what this means is that the iPhone 6 will almost instantly transition from focusing on a subject that's far away to one that's really close, where the iPhone 5s would take a second or so. This isn't such a dramatic upgrade for taking photographs, but it makes a big difference with video: the highly effective digital stabilisation and super-quick focusing combine to produce stunning Full HD video, with much less focus hunting.
Alas, the other major upgrade – optical image stabilisation – is restricted to the iPhone 6's big brother, the iPhone 6 Plus. Even there, Apple is restricting its use to low-light conditions and stills. It isn't used in video mode, presumably to save on battery life.
What this all boils down to is that most of what we said about the iPhone 5s' rear camera still holds true of the iPhone 6's. It produces clean, detailed and well-exposed photographs in most conditions, but isn't quite as good as the Nokia Lumia 1020 in low light.
Its digital image stabilisation remains excellent, and produces smooth, shake-free videos. The only difference is that the iPhone 6's improved processing engine tends to apply less aggressive noise-reduction settings, leading to slightly grainier but more detailed photos in low light.
The front-facing camera, or "selfie" camera as we're encouraged to label it these days, also gains from a small improvement. Although resolution remains the same at 1.2 megapixels, the aperture is now a wide f/2.2, which lets in "81% more light", and there's also a burst mode to help capture your best side. It produces more detailed, cleaner self-portraits in low light, but in brighter conditions you'll struggle to tell the difference between the iPhone 6 and the 5s.
To round things off, Apple has added a handful of features to the camera front-end. Top of the list is a timelapse video feature, which produces top-quality sped-up footage, and there's also an additional Slo-mo mode, which captures video at 240fps – twice the frame rate of the iPhone 5s. This is an impressive achievement for a smartphone camera, and the resulting videos look incredible.
Apple iPhone 6: Apple iOS 8
Of course, it wouldn't be an iPhone launch without an upgrade to the software and there's plenty to get your teeth stuck into withiOS 8.
Headline features include the ability to respond to messages directly from the pull-down notifications menu, meaning you don't have to leave the app you're using when you receive a text. The scope of the iPhone's Spotlight search has expanded to include results from the web and the App Store as well as items in your iTunes library; the Photos gallery app now boasts a hugely improved range of editing tools; and the camera app has live onscreen exposure adjustment.
Family Sharing finally makes it possible to share apps and other iTunes purchases with family members, so you don't up paying twice. Up to six members of your household are covered. Family Sharing also makes it possible to let your kids own an iPod or iPhone and associate it with an Apple ID of their own. We found the system worked perfectly when we tried it, even with a fifth generation iPod restricted to iOS 6, setting it up so our test subject was able to browse and select apps for purchase, but only download and install those apps with parental approval from another device.
Open keyboard support lets you install alternative keyboards such as SwiftKey and Swype, however this isn't the best implemented feature in iOS 8. Some apps seem to override the keyboard you've chosen, and it's all too easy to switch back to the standard iOS 8 keyboard by accident. It's just as well that Apple has also improved the default keyboard, then, with multiple word suggestions that appear in a row immediately above the keyboard, rather than the fiddly bubbles that used to appear next to the word you were typing.
Elsewhere, the terrifyingly comprehensive Health app is designed to hook into all your fitness software, although we haven't yet seen any of our favourite third-party apps – such as Strava, RunKeeper and Zombies, Run – take advantage. iCloud Drive finally brings unified cloud storage to iCloud for documents; support for this is built into Pages and Numbers from the start, and other developers can also tap into it.
It isn't all good news, though. As with most new operating system releases, iOS 8 has had its fair share of bugs since it, but some are quite serious: our iPhone 6 Plus would drop its Wi-Fi connection every two to three hours and then fail to find any Wi-Fi networks to reconnect to. An update fixed our problem, but many users of older devices had to wait until iOS 8.1.1 before a fix to their Wi-Fi woes was delivered.
Apple iPhone 6: new features in iOS 8 updates
Fortunately, Apple hasn't only been fixing bugs since the iOS 8 was introduced. Several new features have been added as well, most of which are focussed on helping iOS devices integrate more tightly with Macs running OS X Yosemite. It's now possible to receive and reply to SMS messages across all your Apple devices, for instance, and Instant Hotspot allows your Mac to tether to your iPhone's data connection with a single click - with no need to activate the feature on the handset.
The old Photo Stream app has now been replaced by the beta of iCloud Photo Library. This makes it possible to view all your photos via a browser at iCloud.com, and also removes the 1000-photo restriction of Photo Stream - given enough iCloud storage you can store as many photos as you want.
Support for Apple Pay has finally arrived, too - or at least it has if you're based in the US. Sadly, the UK will have to wait until later in 2015 to take advantage of Apple's contactless payment system.
Apple iPhone 6 review: verdict
The iPhone 6 is a thorough pleasure to use. An iPhone with a larger screen works very well indeed, so much so that we wonder why Apple didn't do it sooner. But the question is: has Apple done enough? In some respects, we'd say they have: battery life is excellent, the display largely superb, the camera as good as any we've seen bar the Lumia 1020, and when it comes to performance, the iPhone 6 kicks every other smartphone on the market into touch.
But, once again, it's undermined by Apple's intransigence on price and upgradability. Supplying only 16GB in a phone that costs £539 SIM-free and commands a huge premium on contract is mean beyond belief, and the fact there's no storage expansion simply compounds the problem. In truth, we wouldn't consider shelling out on anything less than the 64GB iPhone 6 and, at £619 inc VAT, that's substantially more expensive than any other flagship handset out there.
Yet, despite those qualms, the iPhone 6 is so accomplished that to not give it some sort of acknowledgement would be churlish. The Apple iPhone 6 is a superb all-round handset, and at least as good as anything on the market right now – if you can afford it, you won't be disappointed.