This road winds through a spectacular gorge, some fast sweepy sections and a great set of hairpins. watch out for the 'tunnel du tende, a long, dark, narrow and bumpy tunnel with artics coming down the middle of the road at you. Apart from that, a blinder of a road and a great way to get to the Med, or even better, turn off at Breil and take the D2204 to Sospel and Nice.
This is one of the highest roads in the Alps and is a must see just for that reason. The road really becomes interesting as it rises to 2200m odd.