The music in Silent Hill is excellent and I am glad that for the film adaptation they used pieces of music from various games in the series at certain points in the movie. The composer who created the music is Akira Yamaoka who unfortunately no longer composes Silent Hill music (the last game, Silent Hill Downpour has music composed by a different composer).
There are some additions made to the original scores for the film but in my opinion they don't ruin the original.