Think the w890i is just the newer version version of the w880i which i currently have, the only difference being that the keys are more flush with the handset and the camera is 3.2 megapixel as opposed to the 2.0mp on the w880i.
The w880i is a very good phone and you know what you're getting with them, kind of like the old nokias, the menus are the same on almost every model, very easy to use and understand. the biggest bonus for me is the size, i like a small phone and being less than 10mm wide, this is ideal, i dont carry a wallet so everything is stuck into my jeans pockets, fags, lighter, cash, phone, car keys, so small phones are good.
Also i think SE have now realised the 'joystick' thing that was used for menu navigation was useless and appear to have ceased using this, which now makes them very reliable phones, nothing fancy mind.