An enjoyable piece of hokum. It's kind of terrible for many reasons but it's also ambitious, genuinely creepy in the second act, and beautifully filmed. I wasn't bored till the very end, when its big ideas are too carefully explicated. It would have been better if it stayed more mysterious, like Richard Kelly's much better earlier film Donnie Darko.
The bad news: the dialogue is generally awful, too stiff and too heavy. This really kills the central relationship between the husband and wife (James Marsden and Cameron Diaz)-- they don't feel remotely real. And while James Marsden rises above the bad dialogue, Cameron Diaz is simply not a good enough actress to do it. It's one of the worst performances by a big star you're likely to see. It doesn't help that Richard Kelly gave her a terrible Southern accent, 1970s stewardess clothes, and a limp. I'm not sure even Kate Winslet coudl rise above that.