Ended up at a 2D showing by mistake, but I often have issues w/ 3D movies. I liked it pretty well. Not TEH GRATEZT MOVIE EVAR!!!!1!, but it was pretty good. A little predictable. The blend between live action and the CG characters was pretty good, but still fairly noticeable. When in the full CG environment, I was very impressed with the quality of the modeling, textures and fluidity of the animation. That's definitely a long way ahead of anything we've seen yet.
My main beef, aside from the impracticality of the Exo-Suits, was that the Navi didn't seem to fit in their environment. Biologically. Everything else had a secondary pair of eyes, trachea at the base of the neck, and 4 arms. The virtual eco-system was very well thought out and designed. But it seemed like the Navi were designed by a completely separate team. I know, they're sympathetic characters, so they have to look more human, just something I noticed. It didn't hamper my enjoyment of the film.
I did like that the Avatars were very different looking that the indigenous Navi. And I knew right away that Wes Studi was the old chieftain!