Personally, I love music in multiplayer. In Call of Duty 4, awesome suspense music played when the countdown timer started running out. In Halo Reach firefight, amazing action music starts when you reach the last wave of enemies and escalates when there are only five left.
I hope music during matches is set on a loop and the loop changes as you complete an objective and progress further into the level. Even better, it would be cool if the music adapted to how well you are doing. If you and your team are staying alive and storming through objectives, cool Matrix-esque electronica music (like we have seen in the trailers) would play. If your team is getting stomped, maybe some more dramatic music should play.
However, I'm not expecting much since we haven't heard anything about it. I just hope there is music during the match and not just in the menus like I said earlier.
If it starts getting repetitive, you can always turn the music off in the options.