After the Nokia E50, I upgraded to the E51 mainly for the 3G and Wifi capabilities. In return I got much more than I asked for. A very fast processor, lots of memory, great screen and a host of connectivity options. To add to that - stunning sleek looks. I believe this is the best smartphone around - considering the fact that it has all the specs of the highly expensive E90 Communicator except for the built-in GPS and wide screen at one third the price.
My business uses: Lotus Notes Push email and calendar from Seven, VoIP on Skype and SIP(Gizmo), Fring IM, PDF and Office documents(I have upgraded to QuickOffice Premium to be able to edit docs, otherwise the built-in version allows you to only read)
My fun uses: 2 MP camera(fair quality), Music Player and FM Radio. The downloadable Internet Radio on WiFi is excellent with a plethora of stations. Mobiola Web Cam eliminates the need to carry a separate webcam while travelling.
One of the best things about ths phone is the keypad which is very tactile and pleasure to use. This is the only phone using which I have been comfortable chatting in Google Talk and composing emails.
The browser is best among but phone browsers and opens all sites as it does on the desktop browsers with full AJAX and Flash support. In fact, this review is being written on the phone. This speaks for the keypad as well as the browser.
Best smartphone around. Looking forwrd for the prices of E71 to come down.