If people actually believe this thing is anything close to a "masterpiece" you're either a child or a very sheltered adult with very poor taste!
This movie was lauded by many people as something akin to Alien or Star Wars, some grand entry into the sci-fi genre. I love the aforementioned films. I generally love science fiction and fantasy. This film did not work for me in the slightest. I think it is also sort of interesting that there are no major Avatar spin offs nearly a decade later, no grand comicon fan fare. Maybe it was not so grand. In the end you'll form your own opinions, this is my why.
It does not work for me because it's a warmed over Jesus myth layered over a first nations story. It is barely competent at that. I can't define the Na'Vi except by reference to cliches. They're basically granola hippies meet the old west natives, and not in a flattering way. I understand little about the humans of the future, outside of mega corps and one dimensional army guys. I had to google the name of the planet this movie took place on. My first thought was Pangea, close. I am not sure I ever understood the point of the birds. I am not sure why an outsider in a cyborg suit is the only person who can tame the off color bird.
Why does any of this matter?
It matters in science fiction. People invented a Klingon language. I wonder what Greedo's people were like, I wonder why there are Vulcans and Romulans. They are all sort of tropes, and rip off certain real life things. Romulans gives it away in the name. To be clear, I do not care enough to learn these things I rattled off, but it's that wonder. The spectacle of good science fiction, for me, is that curiosity. The world, the people, that stand beyond themselves. You learn something about yourself or the real world by reference to that wonder. I couldn't care less about the blue aliens and their Jesus, and I think that is why this film never worked for me.
I think all science fiction is a strange project of building a little bit on what we know to create what could be, Avatar never makes it off the ground for me.