Watch for the many hikers, especially on weekends.
The Cobblestone Trail, though one continously-named trail, has a variety of trail difficulties. The trail begins with a relatively wide, singletrack climb for the first mile or so. There are a few technical spots of exposed tree roots and/or rocks that may or may not challenge you, depending on your skill level.
At the intersection with Orchard Trail
(which continues up and to the left), the Cobblestone Trail continues off to the right and changes into relatively easy and flat doubletrack for about half a mile.
The trail then narrows again and becomes much more technical with rocky portions forcing you to pick and choose your way through a line. An option at the end of your ride is to take this trail back down to the parking lot for a speedy, fun, and at times technical descent. Watch for other trail users.