I use Scrivener for revision, because the format allows me to hop around to different scenes with great ease. I'm a holistic writer, so I don't necessarily write in order, and Word was driving me crazy because it's a linear program. Though, I suspect Scivener will be more helpful in this regard for revision, and I may use Word for for the first draft, where going straight through will be better.
Other types of programs like Dramatica? I've looked at the trial versions -- more for curiousity -- not worth my time. They wouldn't help me at all, and worse, would try to make my writing processes fit into a mold they can't fit in. I think a lot of people hope this will give them shortcuts to writing a book, and there aren't any shortcuts.