It's ok road for transport, there are few interesting things, but not so great at all
The B166 from Niedernfritz to Hallstatt via the Paß Gschütt.
Joining the B166 from the B99 at Niedernfritz you head north passing through the Ski Resorts of Dachstein West. There is some beautiful scenery to admire and although the road surface is good, the road is nothing special in the grand scheme of Austria. There are a couple of nice sections but it is a means to an end.
At the junction with the B162 at Lindenthal you head east and it starts to become interesting. Fast sweeping bends on an excellent wide road surface following the river for much of the way before dropping down to Gossau. Stay on the B166 and after leaving Gossau you hit a very scenic section through woodland following the river on fast flowing roads to Hallstätter See. Turn right for Hallstatt and The Koppen Pass or left For the main B145 and head up to the big lakes around Sankt Wolfgang.
A couple of hundred metres after turning left is a car park on the edge of the lake with an pleasant outdoor cafe.