Honestly, I have to agree with StingingVelvet (Although I have the admission that I gave into pressure from my friends to get Diablo 3....still kinda regret it though).
If I wanted to play online I would have bought it, but as a singleplayer only dude I could not accept the online requirement and it's downsides.
Obviously I was in the minority though, since it is the best selling PC game ever.
Funniest thing about that whole fiasco for me, was that I lined up that night at Gamestop for the midnight release...of Max Payne 3. Bought the special edition that came with the statue and everything, and the whole time there was this rift between all those neckbearded dorks (not literally all of them, but one guy looked straight-up pedo) and myself. I was one of two people there for Max Payne, everyone else wanted Diablo, all twenty some-odd of them. So when I asked if I could see the box early, I liked it, said it was classy and all that jazz. Then the dude picked up the Diablo 3 CE box and said, "BUT LOOK AT THIS" and everyone erupted. Now you may be asking yourself, what is the moral of this story? Don't make fun of the guy whose game worked the night he got it, because yours might not. ;)