We did it last fall going west to east. Its pretty easy, just loose sand at the western end. Not a problem with a 4x4 van. We did it mid week and it was pretty desolate. Camped at Caruthers Canyon (spectacular spot) and Afton Canyon.
I've done it. Also called Old Government Road in places. It passes through private property at times. Tread lightly. Not difficult.
It was the road travelers used because the Indians had water supplies in the foothills. So the road is close to the hills. Now with the car and a convenience store every off-ramp, the highway is no where near the hills and cuts straight down the middle of the valley.