Excellent. It can be a lot of fun. It doesn't move as quickly as a tabletop game, but it certainly accomodates one's schedule and the time allows more thought to go into writing posts. Critias, who I met on a pbp site eleven or so years ago, calls it collaborative fiction. And he's right. Outside of dice rolling it is a pretty cool way to tell a story and not just kill or steal shit.
I actually collected our last big campaign as I ran several mini games at once into a 300+ page pdf novel that's posted in the Fan Fiction forum below (There's Nothing Free In This World). Amost all of it -- outside the intros and epilogue -- is composed of reformatted transcripts of actual posts. There is also a link buried in my tumblr (link in my sig).