"Just a year after the incredibly successful introduction of Lion, customers have downloaded Mountain Lion over three million times in just four days, making it our most successful release ever," said Philip Schiller, Apple’s senior vice president of Worldwide Marketing.
If every one of those downloads represents a paid upgrade, that equates to $60 million in sales at $20 a pop. It's probably not as much, however, as Mountain Lion is offered as a free upgrade to anyone who purchased a new Mac system on or after June 11.
Still, that's a lot of downloads, and users seem generally happy with the update. Mountain Lion currently has a 4.5/5 star rating out of more than 7,050 votes in the Mac App Store.