Pros
GameStop is a great place to work part-time, like for students. The atmosphere is always laid back, and you just kinda hang out and talk video games with all the customers. It's kinda like that movie High Fidelity where they work at a record store and talk music all day.
Kontras
Sell. Sell. Sell. The problem with GameStop is that they pretty much only care about selling. Your sales numbers are the only thing you are rated on (even in annual evaluations). In order to keep your job you must make sure you sell magazine subscriptions and pre-orders for upcoming games. This is even more so for managers (and assistant managers). They are judged on the sales figures for their store. Three bad months and your toast. I worked at a store for a little more than year and we went through three managers. It's tough to do it as a career. However, I know several career managers who are good at up-selling and they absolutely love their job. If you can sell, and you know games, GameStop is a great place to work. If your not much of a salesman, don't expect to last.