It had the right mix of a big-budget blockbuster and a cerebral storyline that ensured that it would satisfy both the geeks and the regular people (i.e fans of Joseph Gordon-Levitt).
Directed by Rian Johnson, who made the excellent high school noir Brick, Looper is a film about assassins in the present who kill people sent from the future.
In crimes that leave no evidence with bodies of victims who shouldn't even exist, a problem crops up. What happens when an assassin cannot shoot the older version of himself who is sent back to close the 'loop'?
Honourable mentions: Prometheus, John Carter, Safety not Guaranteed