Diablo fans, you can start to cry now, for we are corrupting everything.
It's more like they're parodying/mocking ponies. It's cool, though. I never cared all that much about the cow level before, anyway.
The beta is only the first act, and it's pretty short (less than an hour and a half, even if you go for all the treasure). There's only two sidequests, but there may be more in the actual release.
I've played through as the witch doctor (killer Jamaican accent), wizard (hot), and the barbarian (the only one where I actually had to use a health pot).
You can play around with the skill system online: