This is a beautiful route, and well worth it. Don't do it too early in the morning though as you route tracks through many valleys an canyons. Road quality isn't great though compared to the rest of Spain.
Did this route on new years eve 2010. Early morning. Completely deserted. Lots of lovely bends around the mountains and through the valleys. Not a fast route through Spain due to the many bends many of which are quite low speed. But amazing scenery. Well worth a detour for this.