Not only was the plot ridiculously cliched (e.g. Pocohantas and Dances w/ Wolves), it was obnoxious. David Brooks captures the condescension of the movie perfectly. What I would add is that it annoyingly perpetuates Rousseau's myth of the noble savage. That civilization (things like literacy, and representative rule, and division of labor) are all corrupting, and instead we were better off running around naked, bowing before unelected rulers. Another reviewer made Brooks' point a bit crassly. The movie is telling us is that the alien’s need Americans (not the dumb militaristic kind, but the real Americans, the scientists and the Sully types) which represents American can-do spirit who comes in, f***s (the reviewer's word not mine) their princess, learns their battle tactics better than they do in just a few months, mounts that flying thing that none of the natives have been smart enough to do in generations, and united all the tribes as their new dictator.
Still the visuals were breathtaking, and after I started ignoring the plot, was blown away by his achievements in technology, and it had robot suits that fought with giant knives.