I waited to see this in IMAX 3D and it was well worth it. This film was an experience. The only thing that comes to mind as a comparison, is the first time I saw Star Wars in the theatre back in the late 70's - and I realize the gravity of that statement. I am not saying Avatar was equal - but it was a roundbreaking film - the first of its kind - and absolutley mesmerizing.
I know it seems like a long film - but I wish it had been longer.