It all works like it should connected to Xbox Live. Less so when you are offline, the Xbox will not even properly sign me in and I can't play Fallout 4!
None of my games work, I did multiple full reboots and powercyclings to no avail.
Update: Hmm, I was able to play Fallout 4 if I connected to Live, downloaded the update (thankfully somewhat small), went into the game, selected my account, my save, confirmed to use local save, and then went offline after it loaded. This will be really annoying if I have to do this with every game I want to play.
It feels like this big update needs more testing, wow and even with the preview program helping this...