I travelled this route from Brodenbach to Boppard; it starts with very narrow hairpin-turns, only a handful of them, but total ascent is over 100 meters... a spectacular part of the route! Steepest hairpin-turns in the area, it\'s like riding in \"real\" mountains.
The middle part of the road is fairly straight but also pleasant... a bit hilly and with very nice scenery.
Going down the plateau at the Boppard side is great too. The road is wider overhere, with very nice curves, drops down straight into the town. (finding the ferry was tricky, if you have navigation enter "Rheinallee" as the street, that should do it.)