Can I just say that Blizzard's handling of the Diablo 3 launch was a travesty on so many levels? First of all, nothing worked. No one could login to play, despite their stress testing beta and having a large percentage of players sign up and predownload far before launch. Their response was the now internet famous "Error 37," an absolutely useless message for users. If everything was going to be completely broken, they could have at least provided a useful error message saying "We're getting more traffic than anticipated and will notify you when the servers are ready." or something.
Seriously one of the most disappointing end user experiences I have ever had, and there's no way for me to return my $60 download.