The One X is one of HTC’s most important launches ever. The company lost its way in 2011 – too many handsets largely iterative and generally indistinguishable from each other led to a bloated and confused range and a slump in sales after years of seemingly unstoppable growth.

HTC’s response was to say that it would streamline its approach, focussing on fewer but better quality devices. The One series, which actually consists of three devices, is the result of that new approach. And with the One X, the flagship model, it is clear that HTC is very serious about regaining its lost ground.

The HTC One X is quite simply unrivalled in terms of its design and build quality. With its tough polycarbonate shell it feels rock solid, yet is also thin and beautiful to look at.

Our review unit, which was supplied by Clove, was especially fetching in white, and there’s a grey option if you prefer.

It’s also a minimalist design. There are capactive buttons below the screen, a microUSB port on the left edge, which also handles HDMI-out, a volume rocker on the right and power and microSIM slot on the top. There’s no option for adding an SD card (instead you get 32GB of storage, of which about 25GB is available, and a free 25GB Dropbox account), and there’s also no back cover to remove, so you cannot replace the battery.

The phone is big. It has roughly the same footprint as Samsung’s Galaxy Nexus, but if you’re upgrading from a Galaxy S2 or a Desire or Desire HD you’ll find the size increase very noticeable and might benefit from a quick hands-on in a shop before you make your decision.

The X is most definitely a two-handed device, and even stretching your thumb to reach the Back button in the bottom left corner can be a struggle.

To off the One X’s instant impact is the best screen we’ve seen on a phone. 4.7-inches, 720p resolution, a pixel density of over 300ppi. It’s bright (and visible outdoors), ludicrously crisp, and has such wide viewing angles that it sometimes look as though the display has been painted onto the front glass. The glass, by the way, is Gorilla Glass, so should withstand a certain level of wear and tear.

The One series also marks the debut of HTC’s Sense 4.0 software, with a new direction of its own. It retains some of the HTC hallmarks, such as the famous flip clock widget, but is a lot lighter than previous versions, with fewer animations and faster, more responsive performance.

The best bits of Sense are now those that add functionality, chiefly ImageSense, a new and really rather good camera app.

HTC is extolling the virtues of its latest camera, and although the quality is not best-in-class (a title held by Nokia) it is unquestionably ‘good enough’ for most users, and the tweaks in the software make it probably the most useable phone camera we’ve seen.

These include simple but clever things like putting the camera and video buttons alongside each other in the same app, rather than requiring you to switch between them. This also allows you to snap photos while shooting video (a nice idea but harder to use than it might sound) or to grab a frame from a video to save as an image.

HTC says the camera focuses in 0.7 seconds (although it is slower in poor light), and we won’t argue with that. Coupled with a fast burst mode the days of missing shots are long gone.

Elsewhere Sense is starting to become rather superfluous. A new music app enables you to install other apps, like SoundCloud, as plugins, and the selection of widgets is as nice as it ever was, but much of the UI feels as though it is being redesigned for the sake of it rather than to make it better.

HTC One X reviewHTC always says that Sense is essential to help the company differentiate its products from its rivals, but the striking design and enhanced functionality seem to do this far better than a few 3D effects ever will.

But at least is doesn’t slow the phone down. With a 1.5GHz quad-core processor the One X steams along, devouring every task we put it through. There was zero lag in general use, 3D games played smoothly, as did HD video through a built-in app that handles a wide range of popular formats.

Benchmarks actually suggest that the latest dual-core Snapdragon processor used in the HTC One S outperforms the Tegra 3 here, but it’s a moot point. Performance is not so smooth that it’s simply not an issue you will ever have to consider.

All of which amounts to the best Android phone to date.

We can point to a few niggles here and there: no camera button, no visual indicator to show when a shot has been taken, the frequent appearance of an ugly ‘Menu’ button on non-ICS optimised apps (partly a result of HTC’s decision not to use virtual buttons like on the Nexus), the placing of the standby button on the top of the device rather than the side where it would be easier to reach, but none of these amount to a significant complaint. Even the battery life exceeded our (admittedly low) expectations.

In short, the One X sets a new standard for Android phones to match. Now, will the Galaxy S III be up to the challenge?

Have you bought an HTC One X? Do you agree with our verdict? Let us know in the comments below!

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