All those "spoiler-free" reviews are for naught since Avatar's general storyline isn't the most original nor the most captivating, so the story is actually very formulaic and predictable, and the characters are atrociously two-dimensional, but the thing is that Avatar is just too well-directed for anyone to actually care. Cameron's attention to detail in the world he created, and the Na'vi's culture is just so breathtaking that you become riveted when it really shouldn't be. Despite the 2 hour and 45 minute duration, the film zooms by, and it's both a good thing and a bad thing. It's a good thing because the feeling that comes when a movie makes you feel as if you're forced to sit through something and you just feel as if you're just tolerating it, this feeling is almost non-existent. It's a bad thing however because it leaves you with feeling shortchanged in terms of character development. The character development feels half-baked and rushed and overly cut to the point of them being disposable, and I usually don't bring this issue up, but the thing is, I want to care for the characters, but I don't really get that as much as I wanted to.
3D, awesome. Actions sequences, double awesome. Fine, there's like that usual James Cameron staple of 'big bad corporation' and 'big bad military' but in the end it's hard to care about all this because the thing that the movie does very well is make you have fun. Really, that's what the hype promises, and in that aspect, the film truly delivers.
Heck, the 3D itself is worth the price of admission, and the epic action setpiece at the end is a huge bonus. However, it just feels like James Cameron could do much more to the story. He's renowned for being a great director-screenwriter with films like The Terminator and Aliens under his belt so it's kind of disappointing to see how crappy this story is in comparison. Cameron does have plans for a trilogy, so one could say that this overhyped movie is actually more exposition than a complete movie story-wise.
Long story short, go see this piece of movie history in 3D, although you might not like the story.