I got Day 2 today. It's a pack of re-usable stickers. (Including a humorous Kony 2012 one.)
Also, heads up to any other fellow Canadians who signed up for this, it looks like Canada Post kinda fucked up and sent Day 2 to the wrong people. So there may be an address sticker overlayed over someone else's address on the envelope.
The game still looks amazing on 360 but the upgrade has a couple of new side missions as well as FPS mode. To me, it really doesn't matter which version you want to play. It's a great game regardless of which one you play.