So far, I've only heard a few people on the mic, I hope that number will vastly increase upon release.
What NEEDS to happen with GOWA MP VOIP is:
-We absolutely NEED to be able to call up the scoreboard, highlight a name and individually mute that player...if this is not available my personal enjoyment of the game will be VERY negatively affected, as I am driven mad by the players that have music blasting in the background combined with the loud ambient noise of other people in their household.
-It would be great to see a speaker icon next to each player's life bar as they're running around, or better yet a feed in the lower corner of the screen that shows which character is talking when they're talking.
I for one think that SSM will be releasing one badass game, and am looking forward to it. The level of communication Tank et al has had with us is very impressive and appreciated.