I played it at BlizzCon.
Even the clearly unfinished pre-alpha build was more fun and engaging than most full release games I've played recently.
So yeah. I'm pretty excited about it coming out sometime in 2015.
Edit: They've said multiple times that it won't require any subscription to play D3 online.
Skeleon said:
I feel very meh about it.
It might still be good and addictive, but it seems to have lost most of its dark atmosphere.
It's too much like the comic-y Warcraft franchise now.
I assure you, it was very, very dark when I played

The audio journals that you can find actually go a really long way to contributing to the mood. There's one you find that talks about King Leoric and the events of D1, and it was actually pretty chilling to listen to as you adventured through the Tristram ruins.