I've seen a lot of movies, and a few in 3D. This was my first IMAX, and I'll never be able to see a movie any other way.
The visuals were simply stunning, to the point where you cannot tell what is computer rendered and what is live action. The movie is even better than the visual, though: the story moves quickly and doesn't rely on twists and turns. Not enough credit is given to the actors, especially when they are behind the computer effects.
Simply put, this may very well be the greatest movie ever made. Hopefully it won't take Cameron another four years. I say forget the banks and give James Cameron $700 billion, and see what he comes up with next!