I have had a BB 8310 for 3 years now, no complaints.
Except it got wet (soaked) and canīt use mp3 player, camera, video camera, but email, phone, etc works fine.
Wanted a wi-fi capable phone so I purchased the E71 (unlocked, US version from amazon.com) and I am very happy with it.
I also used an unlocked E75 for a day and I prefer the E71.
E75 feels a bit heavier, thicker and personally I want the keyboard ready to use, not hidden.
The phone is great, the OS is very fast and it has all the features I like in a phone. The wi-fi and GPS are incredibly fast and accurate. Its nicer, sleeker, the camera is better (not great, better than BB8310). The quality and feel is much better than the "plasticky" BB.
However, in my humble opinions, there are some cons:
- it takes a long time to set the MFE working. With BB, its muuuuuuch faster. In my case, setting up the exchange mail took me hours of work + several questions to the IT department.
- BB is more "famous", there are more applications and things to add than for the E71, for example Facebook (you can get it for e71, but not dedicated).

In any case, itīs my first Nokia and Iīm impressed with the quality of it.
D.