The entire movie, plot-wise, reminded me of something off of the Sci-Fi (SyFy these days) channel. Nearly every move was horribly predictable, as far as I could see - in fact, I was only 'surprised' by some moves in how predictable they were.
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Jake's whole 'acceptance' into the Na'vi/Omaticaya was... too straightforward. Former soldier goes in, somehow, despite going against _every procedure advised_ is immediately brought on a mission, and his misbehavior brings him a new success rather than... well, getting eaten. Which would've made for a more boring movie, but, visible from a mile away. Despite having no training he somehow manages to get himself inside better than anyone else due to a 'mystical force', because that's the _only way_ to squeeze him in within the confines of the story.
Is Eawa psychic/clarivoyant? If so, wouldn't mankind be far more concerned with those powers rather than the room-temperature superconducting 'unobtanium'?
He goes through the standard 'trials and tribulations' phase, never once misstepping so foul as to put his position in danger. The Na'vi are delightfully simple and 'peaceful'. They're just alien enough to be 'alien' for the movie, but so idyllic and socialist that we can't help but like them. We never see strife in their community, besides Jake's later arc. We don't see any tendencies or cultural differences that we could find 'offensive'. We don't see how they handle the crippled, or the old, or the mentally deficient. We are given _no reason_ to dislike them - the whole setup is so completely black-or-white that it loses all the fun.
So he goes through the motions and, obviously, succeeds without a hitch. Despite the effective ruler's son hating his guts. Because they're so sweet that the idea of political assassination isn't even feasible from them - besides some grunts and snarls, and some assertion to go home, we see almost nothing from the leader's son in terms of _real_ aggression or action.
The language barrier is almost never addressed, and in a matter of _three months_ Jake picks up a language that has absolutely no resemblance to his own, with no mentioned written language, including ear movements. He picks it up handily despite it taking the scientists multiple _years_ to achieve a similar feat. All within the warrior training montage.
The military colonel is also restrictively predictable. (Ex)military man, with a stubborn hatred against the enemy so strong and unmovable that he fights down to the last man - himself. Void of compassion, he's made out to be nothing more than a muscle head - he takes multiple steps in the movie that could've easily resulted in multiple unnecessary deaths (e.g. kicking open the door into the docking bay with only a literal moment's notice, full of valuable scientists and the entire project's leader), and yet he's put into this high ruling position; the movie also implies he was in a similar leadership position before. Motivated more by revenge than by anything else, I really have to wonder why his ass hadn't been previously demoted.
Oh, and not to mention the corporate project leader, or whatever he was. Yes, his disdain for the natives was cute at the start, but they make him so unbelievably xenophobic, so incapable of doing anything but slew half-thought-out insults that, again, I have to wonder how he rose to the position he's in. Like the rest of the characters, he's a stereotype from trashy sci-fi taken and stretched to the limits of the archetype.
Not to mention the unobtanium itself. The movie would work a bit better if it explained _why_ the mineral is so valuable - a room-temperature superconductor. Maybe it'd help to explain, earlier on, that Earth is _trashed_. But the chances that the only planet we've found with this rare metal _happens_ to be inhabited by a humanlike, sentient species is so phenomenally low that it just makes me scratch my head. Also, why not mine the floating mountains (working under the assumption that they float 'cause they're full of superconductor in a major magnetic field)?
Back to Jake. Falling in love with the ruler's daughter was just... awkwardly handled. First of all, he's genetically impure - the chances that he can even breed with her is low. He is physically different, with humanlike traits that make him appealing to us in small ways, but, consider the following - how many people, excluding fetish, would be sexually and romantically interested in one of the Na'vi? Or a human-Na'vi hybrid? Would you be interested in, say, a human-orangutan hybrid? She _should_ find him disgusting, as her father does, and the others, yet he somehow charms the pants off of her to the point where no matter how much _dumb crap_ he does in the movie, she always comes back after an appropriate girlish tantrum. Because Jake's always right, despite being portrayed as one of the least intelligent, least tactical members of the entire movie, second only to the colonel.
And somehow, until Jake comes along, the natives never really manage to mount a successful assault against the company. Why not? They're supposedly intelligent enough, and god knows they _care_. But for the sake of the movie they're somehow unable to realize that their arrows are useless against the great machines, despite the start of the movie even implying that multiple attacks have been mounted against the dozers before. Heck, even lifting and dropping a few heavy stones would do more than their arrows to most of the mechs.
And then there's the whole 'rider of last shadow' business. In _one day_, Jake manages a feat previously only managed by five people prior. With only three months in his avatar body. And doesn't get himself killed. Never is the consequence discussed for picking the wrong... banshee (trying to go for one that doesn't try to kill you) - how did he pick the right last shadow? How did he succeed? How did the thing not just immediately roll him off? In a long line of difficult to believe successes that was about the point in the movie where I gave up on expecting any plausibility to their actions.
Then there's the final battle. Honestly, it's a battle, I'm not going to ask much from plot here. But why do the Na'vi allow the remainder of the humans to escape? Why not send the message of 'stay away, stay far away'? The humans _destroyed their home_, akin to destroying their nation. How would the Na'vi, previously so intolerant of the sky-people as to even disallow Jake and the scientists anywhere near, suddenly decide to let the people who had _slaughtered their people_ leave? Also, what's that one brown guy at the end gunna' do, staying behind? He has no avatar body. He's going to be stuck on a planet, with an atmosphere he can't breathe, probably with food he can't eat, with an entirely alien population.
I'm not asking the movie to have a great plot. I'm really not. But I really can't see how anyone can _appreciate_ the plot, except perhaps for it's sheer simplicity, and the fact that it doesn't make you think. The bad guys are bad, from the start, almost, you hate them. The good guys are good, very good. Jake's only 'fault' is taking up the colonel's mission to begin with, which he promptly forgets about/abandons after providing a few scraps of information. Hating the Na'vi is nearly impossible - they're such a simple, peaceful people so in touch with nature that we can't possibly conceive of them as evil. Cut and dried, _nothing_ in the movie shocked me, which left me a touch disappointed.
The movie was beautiful. I'll give it that. I _wish_ more movies could be that pretty, and if I'm not expecting anything from the plot, both times I watched it were then pleasant. But I'm just... I can't see anyone _defending_ the plot.