We had a lot of fun making Magic On The Dance Floor (a game of my own design btw) but the music was a challenge. It's a music based game but game players don't actually have time to really "listen" to the music. Instead the player experiences music more than listens to it. So you can't get all crazy detailed because no one's going to hear your awesome ghost notes and weird time signatures while trying to read falling arrows and time keyboard presses accurately.
I think this is a healthy compromise of music that needs to be "front and center" in a game without overloading the player.