Even my wife, who has not touched a video game since SSX 2.... so what is that, about 7 - 8 years ago? Maybe more? ( well, except Wii games )
We have barely put a dent in it, as we are only just past talking to Deckard Cain, but that is because my wife and kids ( twin daughters ) have no idea how to play on game consoles other than the Wii. But they are picking it up really fast. And it is so cool, that when I am in the office playing WoW, I can hear them in the family room laughing it up and having an awesome time.
Personally, D3 was bad on the PC for me because my PC is an all in one, with no video card, and it couldn't keep up with the game. I gave up on it rather quickly because of how poorly it played. But playing it on a 65" screen with a great audio system is just awesome.
I'm only writing this because I wanted to tell folks that if they are on the fence about getting it for family use, well, obviously, I say "go for it!"