I ride them all the time. Great trail system, difficult climbs, sweet singletrack, creek crossings, very technical rocky ups and downs. My favorite path is to start at Bells Mill road trail head, climb The Monster and proceed through the yellow trail to Roxborough ave then cross to the other side to come back on the green trail.
I'm actually waiting for it to dry up a bit due to the fact that my current tires are Holy Rollers and I don't think that they would fare too well in muddy conditions. I looked for new tires on the maxxis site the other day but it seems like everything got more expensive, I'm guessing because of Katrina. I don't have 50 dollars to spend on one tire(if i were to buy two of them). I could just get a good rear tire and use my old Earl's up front. Any suggestions for what type of tire might be good that I can get in a size thats atleast 2.1. I saw some Maxxis High rollers on closeout at jenson for 12 bux, i might go with them except they're pretty small, only 1.9 inches.
I'm out on the Wissahickon trails almost every weekend weather permits. As far as I'm concerned, it's some of the best riding within an hour's drive of philly. I'm always up for riding with new folks -- I don't have many biking friends so I often hit the trails alone. Let me know if anyone's interested in meeting up some time. I'm also game for day trips... Jim Thorpe, High Rocks, etc.