GamePolitics.com:

Blizzard has issued an apology to all the players all over the world that suffered through trying to log onto Battle.net to play Diablo III over the last few days. The company says that they have been humbled by players and by the gargantuan task of trying to keep Battle.net servers up and running as millions of people (many in vain) attempted to play the game. As of now, they say everything is stable and players should have no problems logging in.

Some Mac users have also complained about the performance of Diablo III’s Mac version. Anecdotal reports suggest that Diablo III performs better on some Macs running Windows in Boot Camp than natively in OS X.