These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Quaritch. Pretty much every morally questionable action he makes can be seen in more than one light: A murderous, racist Colonel Kilgore, a Badass War Hero who will stop at nothing to protect humanity or someone who believes their actions are completely justifiable means to an end, combined with no small amount of stress.
Is Jake a genuinely good guy, or is he a Manipulative Bastard that selfishly used everyone from the Marines/Avatar program to the Na'vi tribes themselves for his own gain?
Are the Na'vi people compassionate to all life, or are they xenophobic jerks? Or both?
Are the RDA troops fantastical space racists or veterans of endless corporate wars recruited to protect tree-hugging scientists on an alien deathworld, where their enemy is picking off their friends one by one while company PR keeps them from retaliating, forcing them into a no-win scenario where they must sacrifice themselves to protect people who show them utter contempt, and can only take refuge in bleak and crude humor. (Exceptions notwithstanding)
Award Snub: Many consider that The Hurt Locker winning out over Avatar in the 2010 Oscars and the BAFTAs was in a magnitude comparable to Annie Hall winning out over Star Wars back in 1977. There was a running joke among both fans and haters that voters supported The Hurt Locker and Kathryn Bigelow as an explicit means of snubbing James Cameron. Talk about a Take That.
Broken Aesop: Very much depends on whether or not you interpret the film as being anti-technology:
On the "yes, it IS anti-technology" end, there's the troublesome (and not all that subtle) implication that the Na'vi's ability to live in technological simplicity and harmony with nature is an example mankind should learn from...despite the fact that they're a warrior culture and seem to have easy, naturally supplied access to a lot of things humans had to develop complicated technologies for (domesticated animals, medicine, shelter, etc.).
Not to mention the medium itself, where themes like the beauty of nature, simplicity, and forsaking technology are being presented to us in an enormous budget film whose marketing was largely centered around a technical gimmick.
In the "no, it's NOT anti-technology" corner, there's the fact that the scientists in the film are portrayed in a positive light, that bit about Trudy aiding the protagonists by using some of the military's advanced technology against them, and the general Technology Porn nature of numerous scenes. To this camp, the general consensus seems to be that the film is less a critique of technologically advanced lifestyles than it is of militarism, imperialism, and out-of-control capitalism.
Dancing Bear: The whole fuss about the technological achievements necessary to pull this movie off: 3D digital film cameras, motion capture refinements, etc. Arguably the never-fully-disclosed but definitely astronomical budget and the marketing-induced hype.
Quaritch is not the main character of this movie. He is, in fact, a villain. The villain.
Grace, the compassionate doctor who taught the Na'vi English, played by Sigourney Weaver. Probably the movie's most genuinely sympathetic and noble character. Her avatar has got to be the single most incredible achievement in CGI technology ever. Sadly, she's also the designated casualty meant to pull at our heartstrings. But at least she becomes one with Eywa, a truly worthy final fate for her.
One of Stephen Lang's (Quaritch) earlier roles was in Tall Tale, where he played a farmer standing-up to a mining company from developing a fertile valley.
Before the Memetic Badass Quaritch became Lang's most notable role, his previous famous role was Ike Clanton, who is the flipside of Quaritch as a completely cowardly villain.
Internet Backdraft: A discussion on if Avatar was snubbed for the Best Picture award by the Oscars in favor of The Hurt Locker will spark a big one. Also, arguing that this movie has any depth at all will spark a flame war in some quarters (This Very Wiki included), and don't try to say that the Na'vi might've been right after all, or make any comparisons to real life events. EspeciallyThe War on Terror.
Misaimed Fandom: Quaritch is understandably subject to this, being an example of both Evil Is Cool and Colonel Badass. It is when people try to defend destroying the Na'vi home and killing several Na'vi in the process that the extent of said fandom gets disturbing.
Motive Decay: Over the course of the movie, Quaritch goes from being paid to keep people alive to a psychopathic and genocidal quest for revenge.
People would accuse Avatar of being a ripoff of something fairly recent when James Cameron had publicly stated that he had been inspired by something far older. Oddly enough, no one would have said John Carter of Mars. Though it does not contain the environmentalism aspects Avatar has. (Cameron also reportedly said the film was sort of a sci-fi King Lear.) The script also predates many of the stories that people complain are 'too similar'.
Strugatsky Brothers' Noon Universe had a similar planet, complete with wildlife and the native tribes. The planet's name was... Pandora! Russian readers have drawn much attention to this, and Boris eventually commented: "The americans have borrowed our idea. That's quite unpleasant, but we wouldn't sue them for that, now would we?"
Rooting for the Empire: Being that the villains are humanity, a number of viewers found themselves rooting for the RDA.
Uncanny Valley: Many say Cameron has averted this by making the Na'vi look human and likeable, but just shy of creeping into uncomfortable territory. Specifically their eyes. Cameron noted that CGI humanoids tended to have "dead eyes" so he took extra care in filming the actors' eyes during motion-capture filming. He may have gone too far in the other direction.