We've done it a couple of times and really enjoyed it. It's well organized and run, the course is a nice mix of different types of roads (pavement, dirt, double-track), they have good feed stations and a nice lunch at the end. The atmosphere is fun and festive. We plan to do it again this year if it doesn't conflict with any other events we want to do.
One caveat is that we've seen a lot of racer types try to do it on road bikes with skinny tires (25 - 28mm) only to suffer flats on one particular section of flat double-track (pinch flats, I think). There were dozens of them. Then again, if you're on this forum, that's probably not an issue for you.
