Pros
If you're a musician, and can complete a few thoughts in a row, you can do ok at Guitar Center. It is a completely commission based job, with the "base pay" being an hourly minimum wage, which must then be faded against. So, a musician can make minimum wage by simply hanging out around the gear that they love. A motivated one can make an alright wage, provided they don't turn around and spend the entire check on gear or vices.
Cons
Guitar Center salespeople get some of the worst reputations of any retail employee out there. It probably has a lot to do with the way they're paid and trained. The training system is marginal at best (you better know something about gear and sales before you get there) and there is very little oversight. As far as the commissioned sales guys are concerned, I'd be willing to bet that only about 20 percent are earning above the poverty line. Of them, only about 3 percent are earning a competitive wage (i.e. enough to pay a mortgage, raise a family, stay out of debt). Store managers and anyone working at the corporate level likely make a reasonable living wage. Sales managers are asked to take a pay cut from their previous year's salaries, with monthly bonuses intended to make up the difference (no guarantee of that happening of course) Assistant managers have the worst gig of all, having all the responsibilities (time and otherwise) of a manager, while still being a commissioned salesperson. Combine that with the usual shady dealings and in-fighting that comes with salesguys on a salesfloor, and it adds up to a completely thankless position. The only reason to take the job is the commission percentage rate hike, which still doesn't make the wage truly rewarding.