This film got me really excited about 3d-films. It's almost funny, I suppose it was like this for people when they saw moving pictures for the first time 100 years ago. Before this going to movies hasn't been anything special for me, but now I'm actually interested about it, and will probably go and see everything 3d in the following months. I just saw Up, and it was quite nice, for it's plot too.
Someone said that the 3d in Avatar looked like there were just separate layers, and I noticed now, that this is probably because the ground is seldom in the picture. The deepness of human face for example contrasted to the deepness of a room is very small, so it looks like that. But when there's something visible in the picture that extends to the deepness-dimension, it looks different.
Also Avatar used traditional means cinematographically, which distracted me at first. For example, I thought that 3d films should not have close ups, and the camera shouldn't move much, or it should rather move as some person or vehicle (that is: if it has to move). Scenes shouldn't be cut at all, if possible. In short: more theater-like, so that the watchers get more immersed.
The scene where the dontrecallsaurus attacked Sully was in my opinion quite unfortunate with it's very fast cuts and confused picture usually used in action pieces. It would have been better if they had tried to picture that as clearly as possible, and used the 3d-technique instead of fast cutting to impress the audience. Of course for the movie's sake it's better not to exploit the 3d-thing too much, and I'm glad they didn't, but if the other alternative is confusion, it would be very ok.
Of course all the suggestions above might make the film only worse, but it just seems to me that the way 3d-movies are filmed must be different from the usual.
Did you btw have trailer of the coming Tim Burton-film? It was pretty amazing, as that smiley cat (don't know what it is in English) came almost to my lap. Pretty scary actually.