My insurer urged me to move to the N8 when my N900 couldn't be repaired.
I liked the N900, when it wasn't away for repair or sitting in by backpack until I had a chance to send it back. The fact that the operating system wasn't being upgraded prompted the switch.
I think I found my way around the N900 much more quickly than the N8, the WiFI seemed more sensitive, the speakers were infinitely better, I made great use of the keyboard and while I don't understand touch screen technologies I liked the N900 screen better.
Having said all that I think I will be happier with the N8. The camera is great for stills and video, Ovi Maps can actually be used for navigation, and the connection to TV is brilliant,whereas the N900 connection wasn't worth using (unless I hadn't figured it out properly). I am withholding judgement on N8's email - so far I haven't been able to use it the way I expected.