You're going to hear this a lot, but there's really no other way to say it: 'Avatar' is a mind-blowing and thoroughly entertaining immersion into another world, unlike anything you have ever seen before.
Much has been said about the groundbreaking 3-D technology created for the film, but what makes it so astonishing is that the effects are utterly seamless - so much so that after a while you are barely even conscious of them. The real breakthrough comes when the Na'vi and the creatures that inhabit their world become just as real to us as the humans.
Yes, the story is overly earnest at times, and the dialogue could really have used a few shots of Cameron's trademark humour. But in the end, Avatar has everything you could want from a movie plus a few things you never even imagined possible.
Even with the script's flaws, I'll give it five stars.
(Wow. It seems that, despite his best efforts to hate it, Murray loved Avatar as much as I did!)