It's definitely worth the drive; last summer I would spend my days taking the train (from the Shore) all the way to Minto and riding in from there. Even if the Rock trail is all you do, it's still probably worth it, but there's a lot more to explore there and something for everyone, whether it be ridiculously tight XC single or some of the more FR stuff off the 5-ways junction.
Check out the area on OpenCycle maps, all the trails are marked and named on those maps. iOS users can use MotionX GPS to get those maps and GPS location on your phone. I'm sure there's an equivalent Android app.
EDIT: just realised you were asking his opinion, derp