The highly anticipated Sony Ericsson Xperia X1 has finally arrived and we've had a chance to play with one for a little over a week.

We wanted to love this phone, but there are just too many niggling little faults that keep getting in the way and detracting from the overall experience.

The X1 has a lot going for it, however, and as the first model in the company's new premier Xperia brand, it bodes well for what follows.

We'll start by looking at the chassis. Given that the X1 is a fully featured smartphone with a slide out keyboard it is surprisingly compact. The device is solidly built and the brushed metal body feels good in the hand and doesn't collect fingerprints like some metal cases. Similarly, the slide mechanism is sprung and doesn't feel like it's going to start slipping any time soon.

With the help of HTC, Sony Ericsson has broken away from Sony's proprietary mindset when building the X1, and as a result it features a standard mini-USB port for charging and PC connectivity, a standard 3.5mm headphone jack and a microSD slot for expandable memory.

The front of the X1 is dominated by the 3in WVGA touch screen running at a resolution of 800 x 480. The screen is very impressive; colours are sharp and the touch element is nice and responsive. However, it is here that one of the little niggles surfaces as the screen is slightly recessed, meaning that trying to touch anything on the edges, particularly the scroll bar, can be tricky.

Below the screen are a pair of context buttons, call pick up/end buttons and OK and X-panel keys (we'll discuss the Panels a little further on). Between these sit the optical joystick and the four-way navigation buttons.

Essentially the keys are pretty easy to use with the exception of the up navigation key which often meant we ended up pressing the select button while trying to move up through a menu or list.

The optical joystick took a little getting used to, but worked very nicely, and having the option of sliding your finger over the pad to scroll or select items is very nice for one-handed use and has the added bonus of not leaving fingerprints on the screen. There is also a stylus, although we hardly ever used it as pretty much everything can be done using a finger or the other controls.

There are four LEDs embedded in each corner which can be configured to flash in various ways when there is a missed call, incoming message, low battery and so on. But because they are located under the case they aren't particularly noticeable in normal light.

The slide is slightly curved and the keys are nicely spaced, but in order to create a gap between the keys, there are no numbers and there are no arrow keys meaning you have to constantly use the function key to enter numbers and you have to move your hand up to the directional pad or the optical joystick in order to move the cursor around.

The keys all have a good tactile feel to them, except the space bar which feels more like a soggy marshmallow. Typing on the top row is also tricky, even with thin fingers, as the front panel is just a fraction too close.