OnePlus has a formula: make phones affordable. We're huge fans of the OnePlus 2 handset, which effectively carved a new standard by delivering near-flagship quality for a middling £239 price-point.
With the OnePlus X, however, the formula has been tweaked. It's a smaller, slimmer and even-more-affordable £199 handset with 5-inch AMOLED display that, on paper, sounds every bit as enticing as its bigger brother OnePlus 2.
But, as we've come to find over the last 10 days of use, that's not quite the case. Indeed, the formula has left us thinking OnePlus X = Y?
OnePlus X review: Premium aspirations
Swapping into the OnePlus X from the OnePlus 2 - the latter which we've been using for a number of months - and it's immediately evident just how much smaller and slimmer the 5-inch X feels.
It's a slender 6.9mm thin, with flat cut-and-polished "onyx" glass panel to the rear, Gorilla Glass 3 panel to the front, sandwiching an anodised and cut-groove metal chassis within (which does scratch, sadly). Such grooves are tactile and give an added aesthetic, although most grip is negated by the smooth glass surfaces.
Just like the OnePlus 2, the X has a three-position switch to the side to toggle between no interruptions, priority interruptions only, or all notifications - an essential element given how Android handles notifications (here in its Lollipop v5.1.1 guise, with OxygenOS over the top).
To look at, and certainly in photos, the OnePlus X seems every bit the premium handset. It's hitting all the right buttons: glass, metal, polish, grooves; there's even a limited 10,000-run ceramic-backed option (that one costs £269 because it's such a tricky material to manipulate - 80 out of every 100 can't be used due to manufacturing processes).
But in the hand, to us, it just feels a bit cheap. Although our hands are touching glass - and leaving a mass of fingerprints as a result - it almost looks and feels like plastic. Which is kind of baffling. Maybe it's the 138g that you'll barely notice dragging on your pocket.
Saying that, compared to other £199 phones, the X walks all over them. Samsung, LG, et al, can't touch this level of build at this price point. It'll certainly tempt those considering the 16GB Moto G (2015), as that budget handset is even pricier at £210.
In that sense this is OnePlus showing off that affordable formula again. Although there are some apparent compromises: no fingerprint scanner on board and, again just like the OnePlus 2, there's also no NFC (near field communication). So no Android Pay or quick and easy swapping between handsets.
OnePlus X review: Inky black display
However, the display tech is something rare at this price point: it's AMOLED. Unlike its LCD counterparts that means richer, deeper colours and inky blacks without any greyed-out wishy-washiness.
And the blacks on the OnePlus X are so deep that they blend into the device's black colour scheme, making the screen almost pop out of the handset. Views from even steep angles maintain decent colour saturation too.
At this 5-inch scale the Full HD 1920 x 1080 resolution is more than ample, delivering a 440ppi density. It's plenty crisp enough for whatever you're doing: browsing, gaming, replying to emails. It's a glossy display, but there's plenty of brightness to counteract reflections. Just make sure you have the auto-brightness setting switched on.
OnePlus X review: Performance falters
On paper the Qualcomm Snapdragon 801 processor and 3GB of RAM is the kind of top-end specification that couldn't have been bettered only a couple of years back. But in reality, this more-than-capable 2.3GHz chipset it doesn't forge ahead half as well as it should.
We're sure people will throw benchmark scores around to that show how proficient the OnePlus X supposedly is, but when it comes to graphics handling the Adreno 330 is not so hot in this configuration. After loading up a game as straightforward as Candy Crush Saga and we often encounter the game hanging ahead of certain graphical animation - merge a striped candy with a wrapped one and it's not uncommon for a stutter or pause. It's not a constant, though, with ultra-fluid stretches of play interspersed with such hangs and stutters.
We've also encountered issues within certain other applications. One that couldn't be accused of being particularly intensive is the British Airways app, which sometimes slows down to excess, with swipes up and down pages stuttering.
So the OnePlus X's performance falters; it's a mixed bag if you're expecting the very best in all things. Watch a video - no problem. Browse the web - no problem. It's a phone that's typically fluid in its operation, but shows its shortcomings with more graphically intensive tasks.
These kind of hangs simply shouldn't happen with a high-end processor and GPU. The Adreno 330 performed just fine in the OnePlus One, but that was running Cyanogen Mod rather than OnePlus' own OxygenOS re-skin over Android (which performs just fine in the OnePlus 2, which uses the step-up Adreno 430). That brings into question whether the root cause of this graphical issue is OxygenOS acting as an additional barrier.
OnePlus X review: Breathing Oxygen
Otherwise when it comes to OxygenOS we find it quite palpable. In recent releases even Samsung, Sony, LG, et al, have stopped forcing excessive amounts of their own software guff into handsets, with OnePlus taking a similar lead.
That's an important step to free-up on-board storage too, although the 16GB in the OnePlus X is complemented by a microSD card slot (the same tray as holds the SIM) to enable further expansion - something the OnePlus 2 lacks.
For the most part OxygenOS feels a lot like Android, on which it is built. There's an apps tray; you can assemble personalised folders; alerts and settings operate in the very same way as any Android device and avoid irksome duplication - something that's an issue with some competitors.
Elsewhere there are genuine benefits, such as a SwiftKey Keyboard from the off, which is far superior compared to many in-house swipe-to-text and predictive equivalents. OnePlus has also embedded a most-used apps feature, called Shelf, which is accessed via a left swipe across the screen - and we've found ourselves using that a fair amount for quick access.
Just like some other Chinese makers there are oddities on board, primarily with the Gesture controls (which can be individually deactivated). Draw an "O" to open the camera, a "V" to put the flashlight on, or a two-finger "II" to pause/play music. The only one we've left on is double-tap-to-wake, which like LG's use of this control in the G4 is handy.
OxygenOS's shortcomings are in its lackings, however, with things like a gallery entirely omitted. Sure, there's the Files folder, as with many Android devices, but it's just not the same. The lack of a proper gallery is perhaps even more bizarre given that there is an on-board editor to auto adjust, or manually adjust pictures (comprising light, colour, pop, vignette, crop, and pre-set filters).
In terms of life the 2,525mAh battery on board will get you through a single day without trouble - assuming you don't have the brightness up super high for the duration. We've rarely been getting into the red after 17-hour working days, including occasional gaming during commutes, which is a fair but not outstanding performance.
OnePlus X review: Cameras
The camera in the OnePlus X is fairly average, with results exhibiting a notable amount of image noise, in particular in the shadow areas. It's not as proficient as the OnePlus 2's camera, as there's no optical image stabilisation, despite a bright f/2.2 maximum aperture ensuring faster shutter speeds are available for handheld shooting.
However, it seems the camera auto-selects fairly high ISO settings whatever the conditions - even an outdoor shot selected ISO 779 - which doesn't help with the image noise situation. Low-light is even more problematic, colours seem somewhat dull (not aided by the UK weather at the moment), while close-up shots claim to focus but frequently fail - so keep a close eye on focus when near to a subject.
Controls function entirely through the touchscreen, with no dedicated shutter button. A tap on the preview image asserts focus, while pressing-and-dragging around this point adjusts the exposure - acting as the only "manual" control that's available. To shoot a tap of the virtual shutter button is all that's needed, but make sure you're holding the camera steady as it can all too easily produce a blurry shot otherwise.
Some additional photo modes are also available: HDR (high dynamic range) for balancing shadow and highlight detail; Beauty, which softens areas of the face for a supposedly "beautified" result, possibly (not) ideal for use with the 5-megapixel front camera; and Clear Image, which stitches together 10 photos for a super-high-res file which only takes a couple of seconds to process. On the video front there's 1080p/720p capture available.
OnePlus hasn't ever been quite at the fore when it comes to cameras and image quality - the lack of an image gallery should be clue enough to that end - but the X is fine for casual snaps, so long as you don't expect too much.
On paper the OnePlus X reads like a well-balanced equation: for a sub-£200 phone its build quality and AMOLED display put it beyond the competition.
But those two positives aren't quite enough to balance out its shortcomings. No fingerprint scanner, no NFC, and limited graphical performance mar the overall experience. Oh, and you need an invite to buy one too.
So as much as we love the OnePlus ethos, and applaud the OnePlus 2 for continuing to redefine the market structure, the OnePlus X finds itself struggling to find a place. It might read like a 5-star product, one that challenges the likes of the Nexus 5X, even the HTC One A9 - but peel back those finer details and, in its current form, this OnePlus X feels like an almost-there device.