I worked there during college, 10+ years ago, not sure what it is like today. I liked it at the time for the social aspect as well as discounts on things and "unsaleable items" that just happened to fall into my car on their way to the dumpster :dunno:
The pay and raises were not terrific except on Gold Card Day (which I believe they did away with), then again I was mainly a part-timer. When I was there, we did not receive any commission, rather on certain items there were "PM" incentives (Promotional Money, if I recall correctly), which could vary anywhere from about 25 cents to $20. Not all items had PMs, in fact some days I would not sell a single thing with a PM on it. Then again when Bill Phillips was pushing his products down the throats of consumers, a case of Myoplex had a $10 PM at one point, and employees would practically fight for the customers who had the money to waste...er, spend...on 4 or 5 cases at a time. Stores that had a generally wealthier clientele had sky-high PMs compared to mundane mall stores. If you are familiar with Massachusetts, for example I might have made $250 in PMs on Gold Card Day working 4 hours in Solomon Pond Mall, whereas in Natick it was insanity and all of the customers had money, and it was not unheard of to make about $1200 in PMs in 4 hours.
All in all...I would never recommend it for a full-time job unless you don't need the money and don't care about the lousy (at least when I was there) opportunities for raises and advancement. For a young person to make a little money while saving on supps and accidentally having some appear in your car sometimes, it might be a good opportunity.