I'm ridden part of it in Tennessee. It was nice, with some rolling hills. I enjoyed it, but I've heard that the southern part of it the Trace is pretty boring, and I have to admit that even the section I rode was pretty monotonous. At least when I rode it (last June on a Sunday morning), there were more cars than bikes, which was nice, and the road surface was smooth. I've read that certain sections have rougher pavement, however.