One thing that hasn't been brought up yet is the whole linking retail games to your account. So you MUST link this to your account and check for permission with Microsoft every 24 hours to play your retail games. Obviously people have brought up downtime on both sides, no internet connections, etc.
But what happens if you get banned or hacked? You would literally lose your entire retail collection/purchases. Okay, so "don't get banned"
but their ignorance and lack of effort during the MANY annual FIFA hacks don't give much comfort. Heck, the difficulty of even just removing your credit card information seems to show their support isn't something I'd bank on too much. At worst, you could just buy a new 360 system right now and still be able to play the disks and games that you have - not this time around.
Just thinking out loud . . .