Never read the book, and this is one of the few book-to-movies I don't plan on reading ever.
The movie was good for much the same reasons as the old muscle car ads. In an environment where we all have to be politically correct and caring and all that other crap we get fight club calling us pussies and suggesting we grow the hell up and be men. The rest of the movie was great as well, but it's always the "be a man" thing that comes to mind when I think about fight club.
Incidentally, in terms of replayability - until very recently I watched Fight Club at least once a month.