Zukiman hit the description of this road pretty well, including the criticism that it's kind of short - it's 26 miles between the two towns, but the good part is about 14 miles, IIRC. The only area where I'd differ with him is that I'm more inclined to give it four stars rather than three.
Locally they like to call this section of road The Little Dragon after the well known road out east. The length is certainly similar, but I have no first hand experience to compare the two.
The CHP is well aware that this is a popular road, and you will see a fair amount of law enforcement on nice summer weekends.
A great road but short. You could add Moccasin to Groveland to Yosemite in hardly more than an hour, or circle back down from Big Oak Flat (top of Old Priest Grade) to Coulterville on the small yellow road. I did that one yesterday. Some poor pavement but isolated and scenic.
All of Hwy 49 north and south from Mariposa - Coulterville for many miles is good riding, it goes at least a couple of hundred miles north. Hwy 49 has good surface,scenery; at least a "4"!
By the way, any map that shows an airport in Yosemite Valley is suspect to me. The valley is 3000+ feet deep and very narrow, and a national park to boot! Closest airport is Mariposa, and for small planes only!!
Dave at Zukiman77@hotmail.com