A fully believable, flesh-and-blood (albeit not human flesh and blood) romance is the beating heart of "Avatar." Cameron has never made a movie just to show off visual pyrotechnics: Every bit of technology in "Avatar" serves the greater purpose of a deeply felt love story.

It’s been twelve years since "Titanic," but the King of the World has returned with a flawed but fantastic tour de force that, taken on its merits as a film, especially in two dimensions, warrants four stars. However, if you can wrap a pair of 3D glasses round your peepers, this becomes a transcendent, full-on five-star experience that's the closest we'll ever come to setting foot on a strange new world. Just don’t leave it so long next time, eh, Jim?

Avatar is all-enveloping and transporting, with Cameron & Co.'s years of R&D paying off with a film that, as his work has done before, raises the technical bar and throws down a challenge for the many other filmmakers toiling in the sci-fi/fantasy realm.

Once again, [Cameron] has silenced the doubters by simply delivering an extraordinary film. There is still at least one man in Hollywood who knows how to spend $250 million, or was it $300 million, wisely.

The first 90 minutes of Avatar are pretty terrific — a full-immersion technological wonder with wonders to spare. The other 72 minutes, less and less terrific.