Got it yesterday, pretty blown away by how incredible it looks. Although, I actually prefer the 'dirtier' image quality I got from the 3D viewings. It's shockingly vibrant and crisp, to the point where it's actually easier to see the more 'strange' design decisions, still, it's stunning.
It made for my sixth or seventh viewing in all, I don't think the film is nearly as good in 2D, and in fact has given me greater desire for 3D. Avatar is very pretty in 2D, but it's not special. I guess it was the 3D that was.
As much as Cameron banged on about avoiding stupid 3D shots, there are a few that actually stand out as stupid in 2D and don't play at all, Jake kicking up dirt when he first goes running, the triggers on the grenades flying at the screen etc.
Somethings are actually better though, the flicker of objects falling such as the firey ash stuff doesn't jump as much etc. And the film does still give a really great sense of depth throughout. Overall, the video is really amazing, the film is really not.