Of all the times for Xbox Live to be experiencing "limited service". Microsoft's Xbox Live has been having some pretty serious issues for the past hour or so.
Looks like Xbox live sign in is down currently. I hope that isn't our fault!
— Vince Zampella (@VinceZampella) March 11, 2014
Unable to sign in to Xbox Live on Xbox One? We're on the case to get this issue fixed as soon as possible! http://t.co/99xfLNeme4 ^PC
— Xbox Support (1-5) (@XboxSupport) March 11, 2014
If you are having issues signing into Xbox Live, we are aware of it and actively working on the issue. This is not a #Titanfall issue
— Larry Hryb (@majornelson) March 11, 2014
I could sign into my account (both in a browser and on my Xbox One), but couldn't sign into Titanfall or access stores. Your mileage may vary; others can access the stores, but are having trouble signing in in the first place.
Right now Microsoft's Xbox Live service page is saying that "core services" are "limited".