Movies should be about enjoying some popcorn and being interested in what is next throughout. This movie qualifies as a fun movie with really great effects that you aren't "thinking about" all the time. It's not 5 stars for me because the relationship between the key "romantic" characters was hardly developed but the cast was excellent, the action was very excellent, and we are looking forward to "the next one..."
Seeing Avatar in IMAX 3D was without question the most fullfulling movie experience I've ever had. Not only because in well over two hours the thought of "special effects" never even crossed my mind and I was just in another world - but because in the end it is the ultimate love story and if you are not "moved" by it - you better have somebody slap you because you probably don't have a pulse.