Overlooking Four Mile Creek, near the beginning of Shelf Road.
The road is generally well-maintained, with some areas of mild-to-moderate washboarding. A 4WD is not necessary on this road, though some of the side trip options do require 4WD. We were in a stock Wrangler JLU; the Jeep was not in the least challenged by this road. The main thing is to take it slow. We kept it under 15 for most of the way though pushing it up to 20-25 in some spots was feasible.
The road is generally well-maintained, though there is some washboarding in a few spots.
The road is narrow, no guardrails, with some spectacular dropoffs. The hairpins usually have quite enough room to pull over so as to make room for oncoming traffic. If not, it's easy enough to back up a short distance, as there are also sufficient wide spots along the road to let traffic by.
Looking down into Four Mile Creek at one of the steeper dropoffs.
We only met three or four vehicles coming the opposite way, and saw a Dodge van and a small Subaru on the road as well. The road is not difficult to follow, despite several intersecting roads. You do have to pay attention, however, as it is quite possible to get lost for a bit up there.
There is decent phone service (Verizon) for most of the route, so Google Maps is probably your best friend. GPS is solid as well.
This is not a high mountain trail. Don't expect broad vistas of snow-covered peaks. What you will see are some magnificent canyons, creeks, and a changing forest type. We picked up gambel oaks at about 6500 feet, aspens shortly after and many more after 7200, and spruces and pinions starting at 7500. We topped out near Cripple Creek at 9478.
There were still some wildflowers out; blue bonnets, Indian paintbrushes, Queen Anne's lace, yellow coneflowers, Russian thistles.