My wife has the N8, man we were waiting impatiently for that phone! We were so eager to test out the camera, the usb host mode and the HDMI with 5.1 sound.
But now some four weeks later I gotta say that my N900 is far more flexible and easy to use. The N8 disturbs me in many ways (it has a couple of serious updates for wait for, I know), things like responsiveness (yes, sometimes you have to press the finger three or four times just to get a reaction). I have never liked a virtual keyboard, like the ones I've tested on droids and iPhones. The browser experience i just crap to be honest, and applications just suddenly crash or behave strangely here and there. The skype application is not integrated in any way like it appears to be in the N900. The user interface is not logic either, I always press the wrong buttons.

The good things are in the N8 simply put, the camera (fantastic), the navigation and the HDMI stuff. The rest, well I had expected more than this. I love my N900.