Overall, I have had many bad GameStop experiences.  It usually boiled down to a bunch of hipsters or douchebags who didn't have a clue about gaming in general trying to sell me on something I already told them I wasn't interested in.  With that being said, I absolutely love my local Gamestop that opened in 2009.  Though the staff including managers has changed over the years, everyone that works there knows and loves games.  I love shopping there and sometimes just stop if I'm right around there (AT&T, Walmart and just about everything else is right next to or across from it!) I'll stop in and just say hi.
If I get a copy of Game Informer in the mail that gets FUBAR, they give me a new copy.  They always let me know if something interesting comes in if they think I might want it or if I had mentioned I was interested in it.  They called me one day to tell me someone traded in the steelbook edition of Mortal Kombat Armageddon so I could get first shot at it.  I've gotten various promo items, boxes, posters, etc. from them over the last six + years.  They are just an all-around bunch of good people.
I'm not going to debate the trade-in policies because I fully agree, they suck.  But I don't trade my games in and I've also found some rock-bottom prices on games.  For instance, right now is a great time if you are looking to fill out your PS3 or 360 collections because you can get games there for less than a buck.  I don't care if the game is a turd, the case is worth a buck!