I bought my Nokia E51 after much deliberation and research. So I was pretty sure that I am getting the best. Its been about 8 months now and I must say I dont regret a penny buying it. It provided all features that a 20 k phone would provide (Except for touch screen and GPS).
I extensively use most of the features of my phone and I am relishing it. If you are not so keep to have a hitech looking phone, but would like to have all the features enabled at a reasonable price. this is the model. It is handy, though some people do feel that the length is a weeny leany bit more. But I am ok wit it.
The screen resolution is extremely good and so is the UI. Symbian does become slow at times . But I am not sure how the performance of windows phones are so I cant compare. The only comparable products are
HTC S710 and Asus P320