Picked up a black(only color available) E51 about 4 months ago, after days of analysing & looking for a friendly business phone.
Its been a very pleasant experience, with below being most impressive:
Screen resolution & readability
Processor(quick apps), unparallelled in similar range
Design(appears very sleek)
Ease of use(nice buttons, navigation)
Besides, there tons of apps you can download. My favorites are Opera mini, Google Maps, MobiReader & Internet Radio. The included Music Player is good but FM Radio could do much better. Battery lasts well, needing charge alternate days.
Some irks do exist, though mostly attributed to the Symbian OS its stuck with. Google maps exit unexpectedly after prolonged use, the included case has started to lose its borders, no custom equalizer, Outlook Notes sync without Categories, feeble speakerphone & such. Nothing you can live without, but would have been pretty nice to have when the basics are already there.
Overall, an excellent phone with neat features for the price, and its a Nokia!