I camped in site E7 and had a great time. Plenty of space and privacy, the spot is between two curves in a narrow part of the canyon. The combination of the road not getting much traffic (on a Friday only 4 vehicles passed my site all day), the generous spacing between sites (probably half a mile between each one), and the sight lines being blocked by the curves; I truly felt like I had the place to myself. Very quiet, excellent stargazing, a unique setting, and a low price. This site checks basically all of my boxes. The site is all rocks (large deep gravel), I sleep in my vehicle but I would want a pretty good pad if I were tent camping here. There is good shade in the morning and evening (tall canyon walls block the low sun). I drove here in a Nissan Xterra (around 9.5 inches of ground clearance) with no issue at all. I switched to 4WD around site 6, where the gravel gets deep.
On the way back to the highway I was surprised how nice the views were from the earlier campsites on the road. I'd say book sites 1-5 for views (but no shade, the canyon walls start to rise right behind site 5), site 6-8 for the narrower part of the canyon with the walls towering over you, and site 9 is where it starts to open up again as the road continues up toward the mine.