Scenery is incredible, the road itself is steep and has a bunch of 10mph corners. Some nice switchbacks but not a road to ride very fast due to all of the hiking trail pull off parking, it gets very busy on the weekend. This is an up and back unless you are a dual sport guy, the pavement ends at Gross Reservoir.
The ride up Flagstaff is good, but the turnoff to Coal Creek is unpaved. I only went as far as the CO 72 turnoff.
Take Baseline Rd. west out of Boulder, pass Chautauqua Park and rapidly climb Flagstaff Mountain Rd. Very twisty, with bicyclists weaving along at predictably slow speed. Once past Panorama Point though, the bicycle traffic thins out. Follow this road to Coal Creek Canyon road, another twist fest; west takes you up to Peak to Peak Hwy. and Nederland. East down to Hwy. 93 Boulder or Golden. Love these roads.
Lots of curves, nice ride but watch out for cyclists.