It's always nice to know Blizzard is hard at work on the development of their games, but I don't think anybody who's familiar with their process would doubt that to begin with. That being said, here's hoping we'll start to see a more steady flow of Diablo-related news in the coming months as there really hasn't been all that much lately."Just to clarify this was an interview with Rob at the announcement of the game at WWI, and just to avoid any conclusions drawn without watching the video here's the quote:
'I think most of the other classes are actually playable back at the home office, but I'm not going to tell you about them today. And most of, kind of the first act, is also pretty playable, but we still have a long ways to go.'
So you're quite a bit off from "all classes" and "all of act one" being finished. It's really insubstantial information though, because anyone that understands the Blizzard development process and core values we're all about iterating. It's not done until it's done.
As far as information releases go and current development everyone on the team is working really hard on the game, and it's progressing really well, but we're just kind of in a weird spot as far as new information releases go right now."