I have been on this rout last year. Its a nice road, pleasant trip.
If you want to go on any rout in Romania, I recommend you to use an enduro touring motorcycle( i have rented a Honda Transalp from Bucharest). The roads there are not perfect, it had a lot of bumps and sand. The rental company advised me for this bike. And was a good choice. If i had another bike, may be this trip was not so pleasant.
the people are nice and helpful.
They have works in progress and many trucks uses that road, so to go from Sibiu to Sighisoara from this road its veeery tedious. (july 2012)
A nice rural road, with great scenery and some nice corners. The traffic is normal but there are lots cow and horse wagons in the road, so be careful!