Okay, I just saw this movie and yes, it is awesome.
About the plot:
It's everything people say it is, which is to say it's cliched and predictable. But what nobody has said so far is that it's not insultingly so, and I think that is what people who haven't seen the movie might be expecting. It doesn't try to trick you into thinking that it's something more than it is... it just is.
It's kind of like Die Hard. Yeah, the Bruce Willis movie where John McClane runs around Nakatomi Plaza in his bare feet shooting bad guys and pissing off Severus Snape. Uh, I mean Hans Gruber. It's totally cliched from beginning to end... but it's not pretentious. It doesn't claim to be anything more than a kick-ass popcorn action movie. You can just sit back and enjoy it for what it is and not have to worry about it.
Avatar was pretty much the same sort of thing. It's just a cool action adventure movie, and since you already know what's going to happen then you can just kick back and go along for the ride.
About the visuals:
Way better than I expected. People keep saying that they're really, really good, but I couldn't imagine exactly how good without seeing it for myself. A friend of mine told me something that I think puts it best... he said it wasn't like you were watching CG, but rather that these were real blue people. The uncanny valley is gone. It was utterly convincing in a way that I can't describe. And the actors playing these blue people are actually pretty good, so bonus.
Unfortunately, I saw it in 3D. I haven't seen a 3D movie since the days of red and blue glasses, so I didn't know what to expect. I'd heard the new 3D was way more improved over the old style, so I figured what the hell. Honestly, it was just distracting and I wish I'd seen it in 2D. Also, the indoor scenes with actual human actors gave me a bit of a headache because the 3D wasn't as on point as it should have been and was kind of a blurry mess. But the outdoor, fully CG scenes were fine. They looked a lot better and didn't hurt my eyes. I guess maybe full 3D render translates better to 3D glasses or something. Anyway, while they were relatively pain-free that doesn't mean that the 3D was mind-blowing or anything. In fact, there were only a few scenes where the 3D was really impressive. The rest of the time it was either hardly noticeable or distracting on the verge of being annoying.
Anyway, it's good so go see it. But see it in 2D, because the 3D thing is overrated.