There's a disturbing undercurrent in Avatar that's largely gone unremarked. Jake Sully, the soldier who "goes native", is at first glance the hero. In this sense, Avatar is part of a long movie tradition of white men who come to appreciate, side with, and ultimately cross over to the "other": compare, most obviously, Dances With Wolves and Lawrence of Arabia.
But there's a darker subtext to this theme. It's an enduring and unpleasant truth that rich, powerful white men always take what the "natives" have, whether its oil or land, and that is certainly the obvious message in Avatar. But Sully takes something even more precious from the Na'vi: their identity. Becoming them might be the most rapacious form of taking of all. Either Cameron missed this point, or he is being even more subtly subversive than most people have noticed.