The Sony Ericsson W580i is an entry-level Walkman slider phone with some interesting motion-sensitive features such as a built-in pedometer and 'shake' control of the music player.

The first impressions that the W580i makes are generally positive. The phone, though plastic, feels solidly-built and the slider opens and shuts without any distracting 'give'.

One new gimmick - sorry, feature - that the W580i shares with the recently-reviewed S500i is the mood lighting that Sony Ericsson has built into the left and right sides of the case. You can choose from a variety of different colours to suit your mood and also choose to have a mini lightshow as a visual indicator of an incoming call.

Naturally anyone over 25 will view such battery-draining eye candy with disdain but one assumes the Sony Ericsson marketers have got the research to show that the younglings will lap up this sort of thing.

The W580i comes with the standard Walkman array of function keys including the Walkman key, the shortcut key, the two soft menu keys and the main navigation keypad which also double's for the music player's controls. There are a dedicated pair of volume controls but no external camera switch (for that you need the K-series of Cybershot phones).

The main keypad is a conventional affair - which will be welcomed by anyone who found the W880i's razor rice keys a pain in the finger. There are strange-looking pin heads dividing the keys but these are purely decorative. All the keys are responsive and reinforce the feeling of solidity that sets this handset apart from some of Sony Ericsson's very cheapest phones.

The phone comes with a bog standard 2-megapixel camera which is cleverly protected by the slider. There's no autofocus nor is there any kind of flash.

That said, the camera is quite capable of taking servicable pictures in sunlight while the mileage you get out of interior shots depends on how upset you get by blurred and discoloured images. Being fair, the camera is no better or worse than other Sony Ericsson phones without flash or autofocus.

The main display is a reasonably-sized 2-inch screen with 240 x 320 resolution and a 262,144-color TFT. In use it's plenty bright enough with clean crisp text and gives a decent indication of what your photos will look like.

The main operating system is the standard Sony Ericsson OS with one main change on the main menu: a link called Fitness. Sony Ericsson is obviously doing its bit to address the obesity crisis because under this link are a wide variety of fitness-based applications.

For instance, a Walking application is activated by default which keeps track of how many steps you've taken during the day along with the distance you've covered. This can be quite depressing if your office is as sedentary as the Know Your Mobile bunker. At the end of each day, the application resets itself and you start again form zero.

There's also a running program which keeps track of your time, speed and distance covered. Both these applications can be configured with detailed data about your age, sex, weight and height to provide handy info such as calories burnt while also keeping track on how you've been performing over time.

All the information is stored in an .xml file which opens up interesting possibilities - such as comparing your athletic performance with other Sony Ericsson users around the world.

This is something which Nike and Apple have done well with the Nike Plus range of shoes and sensors which plug into the Apple iPod. There's nothing like that level of sophistication in terms of interface or execution on the W580i but there's no doubt that the pedometer does work as advertised and can be reasonably accurate if people will take the time to calibrate it properly.

We suspect that most people will take the occasional look at their step count, think 'Blimey!' and never concern themselves with that particular menu link again. But maybe that's just us coronary-seeking layabouts.

More useful is the Walkman 2.0 music player software. This is slightly more logical in terms of its artist, album, track organisation than the previous version but if you're used to the iPod's intuitive interface you'll still feel slightly frustrated.

Navigation always seems to take one click more than it should and the handling of playlists/music queue needs you to wean yourself off the iTunes way of doing things. On the plus side it can now handle album art (yay!) and play back a wide variety of audio files including the Apple-friendly AAC (.m4a) files.

One unique feature of the W580i's music playback is 'shake' shuffle: press the dedicated Walkman button and give the handset a shake to skip to a random song in your music library. Once again, you suspect that anyone born before 1980 will greet this feature with a bewildered shrug.

What isn't debatable is the quality of the W580i's audio playback once you've replaced the cheap and nasty ear buds with something half decent. The sound stage is impressively deep and even the bass - traditionally an Achilles heel of mobile phone audio - is rich and involving. The phone also supports full stereo A2DP Bluetooth if you fancy splashing out on some cool wireless ear candy.

The W580i has 12MB of built-in memory and is supplied with a 500MB Memory Stick Micro M2 card. Unlike the Sony Ericsson W850i slider this phone only has EDGE rather than 3G, so it's not an ideal handset for web surfers.

But it does include two cracking online apps that don't need a lot of bandwidth: the first is the magical TrackID music recognition software that can identify and name any track playing aloud using the W580i's microphone and matching the sample against GraceNote's online database of millions of tunes. The other is the built-in RSS reader - which downloads headlines and gobbets of text in the background and is a joy to use.

People who like to pimp up their phones with themes and other custom tomfoolery are well served. Sony Ericsson is commendably open and encouraging when it comes to DIY skins and embellishments - they even release their own Theme Creation software to encourage punters to roll their own.

And the W580i can take such themes into an extra dimension with the inclusion of its exterior lighting, vibration effects and its support for Flash Lite animations. Bada bada bling!

So overall the Sony Ericsson W580i is an impressive Walkman phone - as long as the lack of 3G is not a deal breaker. It's good looking, solidly built and comes with an impressive array of features and software.

It's obviously aimed squarely at the younger end of the market - the baggy-jeaned chav wearing a hoodie in the phone's demo movie is a giveaway - but even middle-aged men like this reviewer found the handset a pleasure to use. Oh and guess what? I've walked 872 yards today. Coolio...

Sony Ericsson W580i technical specifications.