The Sony Ericsson Xperia X1 smartphone is without a doubt the hottest mobile from Sony Ericsson this year - find out why in this review.

The Sony Ericsson Xperia X1 smartphone has almost everything you'd need, and is supposed to be a strong statement that the developer is a force to be reckoned with in the coming years. But while the potential is certainly there, there are glaring misses in the execution.

Sony Ericsson Xperia X1 contains many features previously unseen in Sony Ericsson mobiles. Their earlier products in the smartphone segment have featured limited new ideas and have been tainted by the slow, somewhat illogical UIQ interface.

In contrast, the Sony Ericsson Xperia X1 contains everything but the kitchen sink and uses Windows Mobile 6.1. This gives it a lot of advantages compared to its predecessors, but also highlights some less impressive aspects. It also lacks a bit of the Sony Ericsson "feel" in several ways.

The outside of the Sony Ericsson Xperia X1 features an eye-catcher we have requested for a long time from Sony Ericsson with regards to its Walkman music phones; a 3.5mm plug for earphones. This is a first for Sony Ericsson and, as far as we've seen before, unique for any Windows Mobile-based phone. Kudos. Most of the phone is solidly built with a metal shell, but the front button are made of almost ridiculously unstable plastic, which taints our first impressions.

A fun feature of the Sony Ericsson Xperia X1 is the navigation cross, with a central button that doubles as a touchpad. It's not entirely to our liking since a mouse pointer is nowhere to be found on-screen, a feature better implemented in, for instance, the Samsung I780 earlier this year.

Now you use it for scrolling instead, but we find old-school clicking more effective. We find another use for that same navigation cross when the keyboard is extended, since there are no directional arrows in the keyboard. After using the perfect five-row keyboard on the Sony Ericsson Xperia X1's cousin, the HTC Touch Pro, it also bothers us a bit that you have to use the function keys to access numbers.

Apart from that the Sony Ericsson Xperia X1's keyboard is good, with slightly raised separate keys sitting a millimeter apart. It's rather comfortable to write on, but, again, not as comfortable as the HTC Touch Pro's equivalent.

There's a good reason that we keep mentioning the HTC Touch Pro, as both phones are more or less identical hardware-wise. The 'Sony Ericsson' Xperia X1 is being manufactured by HTC, though Sony Ericsson has gone to lengths to communicate that they have developed the phone without HTC:s input. Even so, it makes sense to compare the two, as both phones are based on Windows Mobile and also are in the same price range - at least on the Swedish market.

The Sony Ericsson Xperia X1 has a little more RAM and the display is 800x480 as opposed to the straight-laced VGA resolution in the Touch Pro. This gives the screen, and consequently the entire X1, a slightly longer and more narrow shell, which also explain the lack of dedicated number keys on the keyboard.

The Windows mobile base in the Sony Ericsson Xperia X1 has, like all Windows Mobile-based touchscreen phones, been supplemented with a homegrown graphical interface called the X-Panel, since the system itself is the textbook definition of the word clutter.

The X-Panel consists of a number of different start screens shown either as a grid or as a fan. The only screen you cannot replace with any of the built-in (or downloadable) alternate designs is the main Today screen that acts as Windows Mobile's foundation. Applications include a media file drawer we've seen in other Sony Ericsson models, a calendar screen, radio, Google search and so on.

The best screen we've seen during the test is available for free download and is an adaptation of the SPB Mobile Shell; it simply shows everything the regular Windows interface does, but beefs up the size to facilitate use of your index finger instead of the stylus.

NEXT PAGE: smart ideas, execution: not so smart