Absolutely astonishing route. Short but oh so worth a long detour to get to. Dont forget to do it again the other way !
There's a reason this route is closed at weekends and that's because it's, or was, a Mecca for the local biking nutters. There is a vintage hill climb race staged every year about August time with lots of good'ol German bier (hopefully I can attach a few photo's). The scenery is fantastic and the curves are knee down (if you want). Going up the mountain is not to bad, but coming down can catch the unwary, so be careful!
It's not the longest route on the planet so I recommend riding on to Garmish Partenkirchen (25Km) as it's worth it. Have your "Kaffee und Kuchen" and then ride back to Kochel am See to go back down the hill. Try not to throw your cake up on the way down.
Not as nice as Bayrnzell, due to corners being blind mostly, because it is shorter and not rideable on weelends (closed to bike traffic in one direction).