I'm not going to judge the service before it goes live, but I'm definitely curious to see how it turns out—I'm also a touch wary, given the parties involved. Retailers have been complaining that Groupon produces deal chasers, not a stable customer base, but that might not be as much of a problem for the live-music industry, where the customer base has always been a little unsteady. Also worth considering is the worrying amount of control that Live Nation—which now owns Ticketmaster—has over the live-music industry. I just don't trust them and I never will. GrouponLive's deals might turn out to be great for the musicians involved, but even if they aren't, touring acts might have to take them anyway in order to use Live Nation's extensive national network of venues.
But like I said, maybe it will all work fine. People like to bag on Groupon devotees for being a bunch of zombies who'll buy anything you put in front of them, but pointing them at the live-music industry sounds like a good thing for musicians, as long as the terms are right.
I'll follow up as soon as I can learn more.