I've used it before and I'm using it for my Las Vegas DFRPG campaign starting up today (
http://www.obsidianportal.com/campaign/welcome-to-las-vegas -- there's not much up yet except a teaser blurb).
I agree that the adventure log as a quick refresher is the most useful piece for the players. I like using the wiki as a convenient way to sort and look of notes, but my experience is that players usually don't really care that much about the wiki* (there are exceptions, but I think that's the norm), so the GM should use the wiki as a tool for themselves and focus on what's helpful and not bother with the rest.
(* Interestingly, I'd say that the
more content you have up in the wiki, the
less likely players are to look at it...)
-John B.