Of all the 4e releases, and this may just be my sadistic DM nature, none rides with so much expectation as this book. Not only will usable crunch be a factor (to be fair I'd throw on magic nipple rings... clearly Azmodan did), I also want a heavy dose of flavor and content. BoVD can so easily turn into a hot moss without an expert lead designer weaving through what in any other supplemental book would be considered unfocused and seemingly random materials. I mean the binding theme being 'really evil' is almost laughable when you think about it for its universal usage in just about every supplement involving a villain or obstacle. Still, I, and I bet many others, desperately want to see it done, with juicy representation of both iconic and new villains, and done well. It has to be, or else it won't stand up.
I've liked a lot of Rob Schwalb's work, but I think one author on this book was a terrible idea. I would have much rathered 20 authors, each inputting for a villain or chapter, giving me a range of style and approach as well as crunch and flavor. Now it all rides on Rob's shoulders, and this project is definitely a hit or miss. It's still too soon to tell if this book works yet or not. I can't say that the previews really stimulate me so far, though.