It will be equal to the N8 in terms of speed. Which means (compared to N900) a faster GPU, slower processor. Better keyboard, according to reports.
The UI will probably have a higher framerate, but will not neccesarily be faster to use, especially compared to a tweaked N900.
Video recording will be much better.
Screen is bigger, but with lower resolution.
The browser seems to be slow, but a major update is coming up.

Will it be better? Not for me, or for the majority of the people here, for many others, maybe.