If you ride down from the top, it will be all downhill except for about 150 yards at the beginning. One can take a truck up the Inman road up to the field at the top fairly easily, it's about a 45 drive. It is fairly steep, so going downhill will require some decent brakes.
As for obstacles, it varies depending on how much the runoff of the year affected the trail, usually there are some rocky sections to drop down over and lots of roots. The bridge at the bottom of the canyon is in pretty bad shape.
There are a few times that the trail crosses the creek in the bottom of the canyon, and while some are not too bad (again it depends on the year), you might get pretty wet going over some of them. The few bridges that cross it are in good shape, even though there are sometimes trails that don't follow them.
Overall this is a fairly easy trail, one that goes through some beautiful country, and truly is pretty well maintained. Expect to see dirt bikers, occasional hikers, and there are a lot of hunters in this area during hunting season, so be courteous.
Note: The area has open grazing for cows; be aware you'll likely need to find a car wash for your bike after the ride!