As of August '05 the trail is in good repair. Because of the heavy canopy, there tends to be a lot of small debris like acorns and twigs. This is not a reason to avoid the trail, however. The canopy provides a lot of shade, it is absolutely beautiful and, a bonus, it's the rare flat place to ride in the area.
At the Nelsonville end, skirt around campus taking the road on the south side and check out downtown Nelsonville. It is suicide to try this on route 33. On the Athens end you can easily check out the East and South Greens of Ohio University. Getting into town requires a steep climb and the campus streets are congested; better to walk. You'll be rewarded with a view of one of the most beautiful state schools in Ohio. In between the two ends you have wild flowers, impressive rock outcroppings, an historic "company town," a scenic river and uninterrupted beauty.
My wife and I rode the Hockhocking Adena Bikeway this past Saturday (12/1/01) from Athens to Nelsonville. This was our first time on this trail and, as your review indicates, it is a very nice, well kept, scenic ride... ...good news, there is a new Porta Potty on the trail between the 10 and 10.5 mile marker. It is a handicap accessible unit and was very clean.