Oh, I'm obsessed with this film. I saw the movie first, then read the book, which I recommend, just because David Fincher did the film so well. It sucks to know the ending before you see the film because the scenes leading up to Ed Norton's nameless character's realization are brilliant.
And dude, Brad Pitt owned the film. Tyler Durden is one of those historic characters you never forget.
And I have to give a shout out to the script. It's so brutal and deadpaningly hilarious and cold and distant at the same time.
Also, David was a genius to splice in the random scenes that were giving you a clue Ed was insane.