I watched it again yesterday. Twice in two days. I never do that. Ever.
Avatar is awesome and spectacular in the old-school definitions of the words. I haven't seen a movie that so captivated me since The Fellowship of the Ring, but even that didn't convey the pure sense of wonder that Avatar did. It's clear how much Cameron revels in the idea of Pandora, from each individual plant and animal to the Na'vi culture to the sheer landscape of the place. It's as if he came up with Pandora as its own entity and ended up writing a movie as his way of sharing his planet with the rest of us. At its best, Avatar is a movie about sheer joy; the joy of nature and the joy of discovery. The moments where Jake, our surrogate, gets to see or experience something only Pandora could offer, whether it be the Na'vi coming-of-age rituals, awkward helicopter lizards, retractable plants, or the rainforest at night, are the best parts of the movie, bar none. It's a culmination of Cameron's vivid imagination, his innate sense of direction (ha), and the sheer visual effects talent of Richard Taylor and his Kiwi Krew, and I'd be content just watching these scenes into perpetuity. They're that good.
My inner screenwriter cringed at some of the exposition (Sigourney's "Your brother the eminent biologist who trained three years for this assignment?" was particularly horrendous), but story-wise, I was consistently impressed with the simplicity of it all. For the most part, Cameron paints his story in broad strokes, never getting bogged down with the nitty-gritty details of his world or his characters. That's not to say they aren't there, or that they're meaningless in the context of the film, but only that they're not the focus. We don't need to know the technical details of what Unobtanium actually does, or the geological explanation for why the mountains float, or exactly why Jake's brother was murdered, or what made Giovanni Ribisi such an insufferable prick. They're there if you want to find them, whether they're in the Survival Guide (or whatever it's called) or in the promotional materials or in the umpteen books and guides yet to be released, but they're just not the focus.
It's hard to write simply. As a writer myself, it's incredibly hard to know all this detail about something you're writing and not stuff it all in there just because it's cool. Or because you're trying to cover your bases to make sure everyone understands what you're writing. Or because you feel the need to flesh out every single character in whatever it is you're writing. To pull this story back to just its main themes, to take something that could have been sprawling and plodding and turn it into an 160 minute film that felt like 85, all of this just proves what an expert Cameron is when it comes to this stuff. A great writer can trim the fat off a story, set it aside, and create something compelling without it. A great writer will make you want to seek out more... anything about whatever you just read/watched. That's where all the backstory goes. That's where you put it. And that's what Cameron did. And my god, did he do it well.