Oh, boy. What a ride, what an achievement. Far surpassed my expectations. I can't imagine why anyone would sit there and try to pick apart the dialogue, the characters, whatever. The story is simple, but it is not childish. The characters aren't necessarily deep or shaded, but Jake Sully is, and that's all that matters because this is his journey. I can live with these shortcomings when so much attention has been paid to the exploration of an alien culture, the most comprehensive I've ever seen. There is certainly a lot of grey area between a great screenplay and a poor one, and this one doesn't deserve to be thrown in with the latter.
Jake's maturation, not only within the tribe but in his interactions with the natural world, is done with a sense of wonder, humility, and grace, so to call the endeavor unsophisticated is ridiculous. With the early exception of the scene where Jake gets all gangsta talk with the animals (something that is far worse and out-of-place in its respective film than anything Lucas has ever committed to screen), I didn't have any problem with the dialogue. Sure, Ribisi was a bit cartoony, but who cares?
As far as the effects are concerned, never before have movements and expressions been captured this authentically. Or spend such time creating a full environment and ecosystem. After all these years, someone finally made it feel real, and then used it to create something very moving at times. What more can you say?
