This is a really cool spot.
Walnut Hollow Ranch is huge! There are several areas to camp, depending on your preference or seclusion. Some are near the store, others are further (also lots of parking for larger vehicles, as we met a group traveling by bus as well). We opted for the further spot, to kind of test it out.
First of all, the views are rather great. From on top of the hill, you can see quite a ways. There were also a bunch of different paths that seemed to converge up where we set our tent too, so next time I visit, I'll have to check those out. It's a bit of a walk to our spot though, so not recommended for the immobile or if you're carrying a lot of gear. However! it is a pleasant walk, with lots of interesting plants to check out on the way (including wild fennel). Also, at sunset there was a ton of fireflies, which was a huge bonus to me. We got rained out unfortunately, so I only saw clear skies for a short bit at night - but it looked like there was very minimal light pollution, fantastic if you enjoy the stars.
Shameless plug for the farm too, but there's a meat store on site. We had to pick up a pack on our way out, which was cooked a few days later. I've already talked it up to a few friends/family members, as it was some of the best I've had in a real hot minute. Highly recommend!