I only took the southern portion from Tazewell into North Carolina, but it was exceptional. Portions were freshly paved when I was on it in September 2011. Lots of nice third gear curves with a few tight, second gear corners thrown in.
This must surely be one of the best roads in this area (if not the whole of the US) Many excellent cornering combinations, good surface and great views. Beware of the drop offs in some places. Seriously good road, try it!