I liked the movie, but as everyone else has already stated, the comic is amazing while the movie kind of misses the point at times. Probably my favorite book, but I haven't read that many. I'd say my favorite thing about the movie was the soundtrack (Yes, even My Chemical Romance's Desolation Row...). My brother who never read the book seemed to love the movie despite it's length (I can't seem to get him to watch or read anything to long, well I can't get him to read anything).
I've only seen the Theatrical Cut though. Saw it theaters, the only R rated movie I've ever seen in a theater that's how nerdy I am, lol, and I grabed the single disc for about $7. I want the Ultimate Cut (Since it has the newspaper stand parts which I loved in the comic and missed in the movie), but it's too pricy, and I don't want to spend that much on a DVD of one movie.