Totally agree with Fur. There have been more than a few issues with the battle.net auth servers, basically it's an entire separate system and you are dependent upon it to be up and functional so you can play. I'm staying away from it until it's either required or gives me some tangible benefit with several months of smooth operation.

It is apparently possible to call Blizzard and have them un-link from a battle.net account, somehow, even though they say you can't.