Blizzard have said that Diablo 3 sold 3.5 million copies on launch day.
That doesn’t include the 1.2 million that got the game from the Annual Pass for World of Warcraft (which included the game), so there were around 4.7 million people trying to access those poor servers on launch day.
Through the following week, that number grew to 6.3 million. Apparently, this makes it the fastest-selling PC game ever, which is quite an achievement.
Our review will be up soon.
Source: press release.