This is a pretty awesome, depressing, thoughtful movie. It's not really entertainment for the senses, but for the mind. It toys with you, leading you through many assumptions about the realities presented to you, until you finally realize what the truth is, and everything clicks into place... at which point the deliciously ambiguous ending comes along. The acting is perfect (loved Brad Pitt in this), the sets are unique, and it's pretty evident that the director knew what he was doing.
In a sentence:
Definitely not something to watch as typical entertainment; it's more of an intellectual exercise, although it's supported by a strong cast and solid cinematography.