John Ottman's score for X2: X-Men United takes the themes and musical movements of the first film and expand them into a much more epic sound.
Whether it's Ottman's opening suite which is quite beautiful or the action oriented pieces like Storm's Perfect Storm or Mansion Attack, the soundtrack delivers what it intends.
It's not quite listenable all on it's own. Out of context some of the music is just tones and high pitched string instruments, and it's not very pleasant. It's a score that works, some of the themes and melodies are great and Ottman is a capable composer.
In the end it's a great improvement, and the pinnacle of the series since X-Men 3's score doesn't come close to the grand nature of this work.