Gamestop is absolutely retarded when it comes to release dates for niche market games. I was following the release of Way Of The Samurai 3, Gamestop was offering an exclusive preorder. But then they were only shipping copies to certain locations. And weren't letting people preorder because it said the game was already released. And still don't have the game even though it's been out for a month. And everyone who called to ask Gamestop about it got a different answer, and the release info in their system started changing randomly on an almost daily basis.
Long story short: Unless the game you're looking for is a Halo-sized release, don't even bother with Gamestop. (Amazon actually being the hero for the WotS release. Besides Bestsku who were charging exorbitant shipping rates, they were the only retailer to get people their copies with a few days of release.)