Spoilers galore. If you haven’t seen it yet, stop reading now.
So about those big ol’ robot suits. Why would you have them carry guns and knives in artificial hands, so that they can be dropped or taken by an enemy? Wouldn’t you just make the weaponry integral to the suit? The only reason to carry a weapon is because it’s not already attached to you. It’s not advantageous. Also, why would the suit fall down when the driver is killed? Makes no sense.
Overall, not enough backstory. Jake Sully’s connection to his own life is so tenuous that there’s really no question of loyalties. How could he side with an angry colonel, who himself has so little depth that he seems to have come out of Dr. Strangelove, but stripped of irony? The colonel offers him legs, but those can be obtained with money, we already know. There’s just not enough there.
We also don’t know enough about why the mining company wants the unobtainium, what it’s used for, or who’s backing them. Is this like the US trying to get heavy water in World War II? Is it like our current thirst for oil? Or is it Alcoa hitting on a copper mine? We know it’s expensive, but not why, and it’s a relevant point. Also relevant is the general attitude back on earth towards Pandora and Pandorans. Why? Because I’d like to know whether a defeat of this small, poorly armed security detail (seriously, no cruise missiles or drones?) will be Black Hawk Down, meaning a hasty retreat, or 9/11, meaning we come back in giant numbers and invade everything in sight.
Of course, what keeps it from being 9/11, or even Dances with Wolves, is the total lack of ambiguity. Because the mining company and its security force are largely men and all adults, there’s no conflict of civilizations. Regardless of the moral right of European settlers to show up and settle on Native American lands, settle they did, and that turned fights with the natives into threats to home and family. Indeed, Native Americans killed and kidnapped whole families, women and children included. That’s enough to motivate serious and even disproportionate reprisals, as was 9/11, and as is every terrorist attack on Israel.
There’s no equivalent on Pandora. Why is the colonel so invested in the fight? There’s no reason at all. He doesn’t even have Jack D. Ripper’s paranoia. Nothing. He just wants to go kill. His character, and the Marines who cheer with him, are an insult to actual Marines, who generally don’t want to go blow up indigenous peoples for the enrichment of corporations (even if that turns out to be the gig sometimes). Marines, or the ones I’ve known anyway, want to fight to defend our country by attacking and destroying those who would attack and destroy us. It’s not pretty, but it’s purposeful. It can turn pretty blunt, like just wanting to kill the fuck out of Muslims, but that’s because they’re seen as a threat to our way of life. Without that threat, I just don’t see the motivation.
So the Na’vi are spared the ambiguity of the Native Americans in Little Big Man or Dances with Wolves because they never encounter a child. And the Marines are given no chance for ambiguity. This same lack of ambiguity is acceptable when the enemy is presented as a kind of implacable evil, as in Star Wars or Lord of the Rings, but it falls apart when the enemy is human and identifiably ourselves.