I would have cut the movie into two parts, with the first movie ending at the fall of the great tree. That'd give a bit more time in the first half for exploring the world of Pandora and the culture of the Na'vi, which for me was the best part of the movie. Truly amazing. The movie really made you understand Jake's reaction to the offer of getting his legs back that night. He was thinking "Legs? Legs? That's supposed to entice me? Out there, I have flown.". The movie worked because you could truly feel the world and it was beyond magical. The most amazing fantasy world ever portrayed on screen, by far.
But the second half the movie had issues, I think, and was a little too skimmed over and shoot-an-up. I'd redo the second half as a whole new movie and hope that fixes things. Certainly, if redone this way, it would have destroyed the whole "formulaic" argument... ending on the fall of the tree would have been ballsy and devastating. Instead of ending on nature rising up to fight back, it'd be about man's unending and unstoppable destruction of nature.
Anyway, I did quite like Jake's story, going from wheelchair bound to exploring Pandora. The visual storytelling on that was really top-notch. Seeing him come back to the real world was painful in a good way. Very sad to see him go back to his real body after what he had tasted. I also liked that they explored the drawbacks of the avatar system, being turned off and what not. I did like the scene where Neytiri meets Jake's real form very good. I just wish they didn't have the "let them have cake" ending of just letting Jake move into the Avatar body permanently. I think a relationship of Jake and Neytiri ongoing with the restrictions of the Avatar ending would have been more interesting.
So overall, I'd say it had the seeds of a truly great movie but was brought down by a few flaws, but still held up by incredible visuals. I'm gonna have to find an IMAX theater to see this again. DVD will not do.