I really enjoyed this film, and must credit Chris Nolan with having a higher regard for his audience than other directors. The film starts fast and doesn't break it's pace till the credits roll, if you are after a popcorn film you can enjoy and not pay too much attention to, this is not it. You need to concentrate from the beginning, and it may well take a couple of viewings to understand.
Fantastic, complex and intriguing, it will have you guessing till the very end and thinking about the nature of dreams and your own subconscious long after you have finished watching. Or at least, that is my opinion. ;P