Tarmac at either end (quite cratered towards Westerdale), with generally superb estate tracks between. Not too hilly, and a bomber descent towards Westerdale. The area is used for sheep farming, so be prepared for the odd road block and mud guards are probably worthwhile.
Good views of Scaraben and the Maiden Pap, weather permitting.
Could also be rerouted at Dalnawillan Lodge to head north to Altnabreac, west to Forsinard, then south on the a-road to Helmsdale. That loop will involve a notoriously lumpy section of the A9 though.