I love comic book movies. I think it's the fantasy of them the complete suspension of fact while still semi-based in reality. Whole worlds of new facts made up about people who know exist in the writers imagination that are brought to life on screen. The first of the X-Men series is great (I have to review them seperately because I'm seeing the third one tonight.). It establishes what mutants are, brings in the major characters, gives you the political atmosphere of how normal people are afraid of mutants. Gives us Wolverine, Jean Grey, Professor X, Cyclops, Magneto, Rogue (and the hair change), and a whole slew of others.
It doesn't move as quickly as the second because it has to do all the set-up, but once you're past that, it's a fun movie.