Not one of the best movies of Hollywood, but it's still an entertaining movie with numerous cameos. It's interesting to see the differences between the writer's pitch for a movie and what the final product looks like. I don't think it handles the tones of the movie perfectly. One minute, it's dark, tense and stressful, and the next minute everyone is laughing and you have no idea why.
It's a really cool idea, but when there are so many expositional scenes and you don't have time to be invested in the main characters, it detracts from the movie experience. Also, the movie needs some room to breathe.