I just saw Avatar this evening at a 3D Imax, and I have to say it is a really good movie. The characters were very connectible, the story had an almost perfect and well-timed arc, some of the visuals were very stunning, and the movie got me going through a wide range of emotions.
I do have to disclaim that this is my first 3D movie (outside the ones at theme parks that do more gag 3D effects). I found it incredible how the 3D sucked you into a scene, and how much more real the actors became. I can definitely see this being the direction movies go in.
But was Avatar the best movie of all time? No. Far from it. The pro-environment anti-war message was a little too one-size-fits-all, and some characters outside the Pandora world were very underdeveloped. You can't compare it to classics like The Shawshank Redemption and Forrest Gump.
Was it the most visually stunning movie I've ever seen? No. Sunshine, 2001, Hero, Sin City, The 300, and The Matrix far exceed Avatar in beauty, just to name a few.
Was it the best human/CGI interaction I've seen? No. Arguably District 9 had more connect between the actors and computer generated alien creatures.
Was it the best 3D movie I've ever seen? Well, I don't have anything to compare it to, but I found the Alice and Wonderland trailer to be much more playful and the Hubble 3D trailer to be crisper and have much more depth.
And is this movie that revolutionary? I find it hard to put on the list with A Trip to the Moon, 2001, Jurassic Park and The Matrix.
But should you go see it? Yes. I'd even go as far to say that it's worth the $15, or whatever you end up paying for it. Just make sure you see it in 3D. I'm not sure if it would have held up without it.