Well, I'll put in what I've found so far (had my N9 since Monday).

Let's ignore hardware for the most part and look at usability, software selection, and general attitude toward software between the two.

First thing I noticed right away was the capacitive multitouch screen. It is very slick and awesome to use as far as the physical feeling goes. But then the down side is the inaccuracy. Either I had to 'break it in' or I've just gotten more sensitive at where I need to click it. That damned back arrow in the lower left corner is a pain to hit if you're holding it in your left hand and you touch it with your left thumb, the whole one-handed use is broken because of that.

Clicking on links is just not as accurate as on the N900.

Next on my list would be that on the N900, since it mostly worked horizontally, I never had to zoom in on web pages, and I could still read them just fine. Not so on the N9 in portrait mode, which it seems to favor.

While the feedback for the vkb is the best I've ever used, it does still take up a lot of screen. There are two applications where this really sucks, ircchatter (which is admittedly beta) and Fennec (same). When you try to configure either of them (Fennec's addons) the keyboard covers up the text you are trying to input. Horrible.

Emulators seem to run better, 'cause of faster CPU, etc. But unfortunately you also end up needing to cover the screen with your hands to play them. N9 needs the PS3Six Axis bits... NOW!

UI usage. I don't know about everyone else, but I used the back gesture a lot on the N900, and it just feels natural to do so. But on the N9, you end up minimizing the application instead of it going back.

incoming call screen; The N900 had one nasty flaw, the Answer and Reject were on the same edge, and probably 30% of the time I answered my phone, I'd pull it out and hit the Reject button by mistake. The N9 just made 'em tiny and next to each other. And the picture of the person calling you is the same size as the application launchers, not a good identification system. But at least you have custom ringtones now!

Anyhow, there are some quick thoughts, I actually drifted off to sleep twice while trying to write this. Time to sleep!!!

slaapliedje

On the whole, I cannot say the N9 is better than the N900. Regardless, I'm more interested in making them both better...

Mr Elop, convince me lumia800 is better than n900, n9... sorry elop ylu will fail.

....

couldn't resist...