Yeah, as we were walking out of the movie theater, one of my friends turns to me and says: So the humans were flying helicopters between floaty islands... why not throw rocks at them? (Or roll boulders, or whatnot.)
So before even leaving the theater, a computer programmer came up with a better battle plan than the movie's space-marine main character.
It took me a little while to realize how colossally stupid the human tactics were, too. Namely the low-flying orbital bomber. Once it's in orbit, all you need are a few rocks to rain down. If the Nav'i could get arrows into orbit, I'd understand everyone surrendering at that point.
The whole wheelchair thing I took as a rich-poor trope. Sure, maybe wheelchairs should have advanced, but I excused it because part of the conceit was that those in power screw over those without. So the rich get new legs or nerve repair or something, while the poor get a technology that's been relatively unchanged for a hundred years. No one has incentive to improve the technology, because no one with money has that problem. Not particularly plausible, but possibly worth the value of the metaphor and incentive in the plot.
But apart from the stupidity of the battle plans on each side, one of the most damning things about the movie for me was the ending.
Hooray, the natives one and just the goody-two-shoes humans are staying.
Well, actually, I'm sure the mining corporation will be back with more firepower, in approximately the amount of time it takes to make a round trip (maybe less if the shuttle is transmitting a synopsis of events). Also, the scientists who were left behind are now living on a planet that doesn't sustain human life with a presumably limited supply of breathable air and food. Hooray?