I had this phone as an upgrade on O2 in Jan 2007 and at that time it was number 2 in the O2's top five mobile phones! I have upgraded in Jan 08 to the K850i because I am a Sony Ericsson fan. This phone is great for use as a walkman with its easy set up of buttons on the front, it can play MP3's as ringtones and txt tones, has three games including tetras, 2mg pix camera which is a little outdated compared with my new 5mg pix camera but the W series are made for their walkman use and the K series are made for the best camera use. Also the phone can send voice txt, email, written txt and picture txt. I have never had a problem with any features on this phone and it is very easy to get used to. The only niggle I have with this phone is that when you slide the phone back down it does not finish a call or programme you are using YOU MUST REMEMBER TO FINISH THE CALL USING THE C OR END CALL BUTTON because the slide function does not act as cancel. I hope this review is helpful to you.