The server issues that plagued Diablo III's first 48 hours or so were certainly unfortunate, but it turns out that Blizzard really did have a good reason for not quite anticipating the server load it endured. After all, who could possibly have predicted that the game would sell 3.5 million copies in its first 24 hours? I mean, I'm sure we all thought it would do well, but that number is something else entirely.
That 3.5 million number doesn't even take into account the 1.2 million who received a copy of the game through the World of Warcraft Annual Pass program. All in all, that means 4.7 million people were at least capable of playing Diablo III on day one. Which is a lot, really.
All in all, 6.3 million copies have been sold/acquired in the week since the game's launch, which, according to Blizzard, breaks the "all-time record for fastest-selling PC game." I don't have my list of the fastest-selling PC games of all time handy, but I'll just assume that Blizzard did its homework before making that claim. Otherwise, they should be expecting a nasty phone call from Guinness.
Records or no records, Diablo III is unequivocally a massive, overwhelming success, and it's only been a week. I mean, I haven't even bought my copy yet. That's at least one more coming! Eventually! When I actually have time to play it...