The Box.
I had no interest (or very little, at least) until I saw that it was Screenwritten/Directed/Produced by Donnie Darko's Richard Kelly and a favourite author of mine- Richard Matheson.
I really enjoyed it. It's hard to say much without ruining it... but this movie was well marketed to keep its secrets intact, I think. Think the Trailer/Ending of Star Trek III, but the reverse where it's not in the trailer. Due to this fact, and the twisty-turny nature of the story, it's sure to keep you guessing until the end.
I would say that if you're interested in the body of work by either or both of the two previously mentioned people- then definitely check this one out. If you like suspense thrillers, check it out. If you want to see Jimmy Marsden in a movie where he isn't killed, kidnapped and brainwashed, or otherwise sidelined in the first 10 minutes... or plays "the other guy" in the love triangle... then check it out. It has a 5.8 on imdb.com, so be warned. But I found it very enjoyable right up until the end. Which we can talk about if someone else sees it.
THE END.