I'm not sure I can say much that hasn't been said already about the film, but here are my true thoughts: If the script is not entirely original, it certainly has some nice touches. That's the worst I can say about this movie - because James Cameron has truly risen the bar of movie making. My jaw was hanging throughout the entire film. They've actually created a world - a beautifully detailed one at that. If for no other reason, this movie is worth seeing simply for the artistic grandeur.
One final word of advice. If ever there was a movie worth spending the extra few bucks on seeing at the IMAX - this is it. It would be a shame to see it anywhere else...