Spectacular scenery and lovely corners but the surface on some parts are not the best. Also look out for the clouds/fog which can come in very quickly which can reduce visibility to a few feet, not what you need when you have one hell of a drop on one side and hard rock on the other!
Much of this is very tight with virtually mo run-off and frost damaged surface. The views however are truly spectacular and on a clear day won't fail to impress. The combination of forests and geological features make for a great contrast, road surface starts off badly, but improves a lot as you come down on the Spanish side.