I just saw the 16 minute preview and it looks AMAZING! Forget about this stupid trailer, it doesn't do it justice. You need to see this in IMAX 3D to really get a feel for the movie, its almost a completely different experience.
Now, the "avatars" and creatures on the planet do not look photoreal to me still. But if you accept that and see it for what it is, you'll love it because this particular CG is the best yet. The thing about the CG is how realistic the animations and facial expressions are. He really did a great job with that, you believe its a person speaking and acting.
The 3D is the best I've seen, every single thing on screen is in 3 dimensions. This is not a 2D background with a 3D character, its completely 3D.
This is an extremely stylized movie. Its very beautiful and colorful, the lighting and effects look spectacular. If I had to compare it to anything, its a more colorful version of Felucia in Episode 3.
So, please don't judge the movie on the 2 minute teaser. It will be a really amazing sci-fi experience.