To be honest, I didn't really understand this. From what my mind can tell, this is only available to PowerUp members of GameStop. Let's say you were to buy a 360 game that were to come out in a few weeks or even months. Once it comes out, you can take your 360 game and trade it in for the newer version for the Xbox One for only $10? If that is true, that's pretty neat. You can have enough time to get achievements, gamerscore, and play it through, and swap it in for a completely new copy for $10. Sadly, it's only for Powerup members which I'm not a part of, and from what I can tell, you only have five uses.
Via OXMMembers of GameStop's PowerUp Rewards programs can make use of a limited time $50 guaranteed minimum credit for five standard edition Xbox 360 games when they are traded-in for a new copy of the Xbox One version of the same title.