I've found it's really contingent on which Gamestop you go to as to whether or not you have a good experience. When I lived in Illinois, I had a litany of different small video game shops to choose from, and yet, every Gamestop I went to had garbage employees that didn't know anything about how to be a good customer service rep OR would force me to say no 3-4 times when asking if I wanted a "protection plan", Power-Up Rewards, or to pre-order games that there'll be dozens of copies of at any store not named Gamestop (or Target, lately).
Since moving to North Carolina, there's nothing but Gamestops & a similar chain called Play-N-Trade. My local Gamestop has mostly kind, knowledgeable, and accomodating reps. The ones in the malls are terrible, probably because they care more about taking care of the ridiculous amount of foot traffic they get.
You'd think the ones in IL would be forced to hire people that would make Gamestop the most approachable choice given all their competition, but just goes to show you a Gamestop is only as good as the people in that particular store.