I love going to Game Stop, it's the best place to purchase used video games and they have some really good deals. Personally, I don't believe in paying full price for video games. The way I see it, it's just a computer program that has been copied onto a blu ray and in my opinion there's no justification for paying $60+ for a copy of a program. I rather wait a few months for the title to get old and just buy it for $25.
My only complaint about Game Stop is there business model regarding trade ins. I'm sure that many of you have seen the commercial where they only offer $9 to purchase a new title and from my experiences in the past that is just about right. I've taken games that were valued as $60 that I received as Xmas gifts there to be traded a couple weeks after Xmas and they only offer about $15 for the trade. The low values for trades is my only complaint. As for positives they offer loyalty programs that allow you to increase the amount that you receive for trades as well as receive discounts for purchases. On some occasions they also offer buy 2 get 1 free specials for pre-owned titles.
Hint: I've noticed that many times, there are hidden gems to be found in the bargain racks that are next to the pre-owned shelves. On a few occasions, I've found fairly recent titles in the bins for less than $10.