A highly random selection of thoughts. Spoilers likely:
--Some are arguing that the film is yet another of that hideous subset of Hollywood film in which a white male protagonist shows up to save a bunch of one-dimensional savages who can't help themselves against an encroaching threat. The movie's flawed, to be sure, but this argument is bullshit for a number of reasons: the natives in question are a rather well-thought out and explicated group, and indeed the hero winds up forsaking his humanity (including his very Whiteness) to pursue his destiny.
--No, the film's politics are unabashedly liberal, and as preachy and overstated as the case may be, it is a rare and pleasant thing to find a big-budget, effects-laden spectacular that has a coherent and humanistic point of view.
--That said, it goes a bit too far in the hippie-direction, with the Na'Vi's rituals clearly idealized human ones, rather than palpably alien ones. (The insipid heal-the-world score by James Horner doesn't help.)
--And though the film is a long one, it rushes through too many things. I'm particularly sad that Michelle Rodriguez winds up as collateral damage; she's a compelling actor when given material as strong as she is, and Cameron just loses sight of her here. All of the material is there to make Trudy Chacon a supporting hero per Han Solo or THE MATRIX's Captain Mifune: we see the beats of her character we never pause long enough to feel them.
In short, however, I enjoyed the experience of the film. Actually, seeing it on the bottom end of a double bill with UP IN THE AIR made for a compelling, two-pronged Hollywood assault on American society, so good times all around.