Once you slide the phone open, the keypad appears. The phone feels well balanced, with the bottom half being heavier than the top. This means that unlike a top-heavy slider phone, you don't get the feeling that the phone is about to slip out of your hand when you slide it upwards.
The keys on the keypad seem small, but are easy to press, aside from the top row that is, unfortunately, very close to the bottom of the top section of the W850i. If you have large hands you might find this means you have to use the tip of your thumb to press the 1, 2 and 3 keys.
The slide mechanism itself is smooth and is also spring loaded so it won't leave you to do all the work like the mechanism on the Nokia N80. You can use the phone with the slide shut by unlocking it using the two top soft keys.
The W850i first and foremost is a Walkman phone aimed at music fans, and it definitely delivers on its promise. With the bundled Sony Ericsson Disc2Phone software you can transfer music on to your phone with relative ease. If you have any problems, take a look at our guide to getting music on to your Walkman phone.
We managed to transfer Kelis's Tasty album, which includes 14 songs, in just over six minutes. The Disc2Phone software will automatically convert CDs into MP3 files and then transfer them on to your W850i if you want to. Alternatively, you can simply transfer files already in MP3 format straight to the phone.
Sony Ericsson has included a 1GB Memory Stick Pro Duo that will store around 240 MP3 tracks. The Advanced Walkman 2.0 music player supports AAC, AAC+, E-AAC+, MP3, M4A, WAV and WMA formats. You have the option to set the player to shuffle mode or loop mode and you can also adjust the equaliser. Other options include enabling stereo widening, displaying album art or visualisations and adding light effects.
The light effects option makes the dedicated orange music button flash to the beat of the track you're playing. It's a gimmick, but looks funky, and will have friends flocking like moths to a flame. Another cool feature is the option to send a friend a track from within the player via email, Bluetooth or infrared. This means you don't have to go back out of the player and find the track again.
The thing that really makes the W850i music listening experience great, though, is the bundled 3.5mm adaptor in the box that lets you connect your own headphones. You can also use the stereo Bluetooth connectivity (A2DP) to wirelessly connect a pair of stereo Bluetooth headphones.
If you use wired headphones, you can also listen to FM radio as well as your own music. The radio looks good and works well, letting you search automatically or manually for stations, see what station you are listening to and save that station so that you don't have to search for it again. It also provides a service called TrackID. This records a clip of whatever song you are listening to and then sends it off via GPRS or 3G to a music-recognition service, which then sends you back the name of the track and artist. It worked with about 80 per cent of the tracks we tried.
The W850i lets you minimise the music player or radio alongside other applications so that you can run several of them at the same time. You can use the shortcut soft key on the front of the W850i to pop up a list to access the ones that are running.
Another important feature of the W850i is the 2-megapixel camera, which is activated using the dedicated shutter button on the left side of the phone. The camera lets you take still photographs and video. In the settings menu you can adjust the shooting mode, picture size, white balance and picture quality. You can also activate the LED light, timer, night mode and shutter sound, or add some simple effects.
You can make further changes to your images using the PhotoDJ application. This lets you change the light balance, adjust the brightness and contrast, remove red-eye, add more effects and insert clipart, a frame or text.
There is a second camera on the front of the W850i for 3G video calls. The 3G connectivity not only supports video calls, but also allows you to download music or games directly to the handset. It makes browsing the Web using the built-in browser much faster than on GPRS phones.