I camped there in early September with a tent and had a horrid experience because the ground was covered with goat head thorns. The bottom of our shoes were covered, they stuck through our tarp and tent and would still poke you in the tent. We could not blow up our inflatable mattresses because they would get punctured. A couple of us slept in the car and a couple others slept on the ground of the tent using a couple sleeping bags as padding.
If you're staying in an RV or cabin you will probably have a better experience there. But the kids kept stepping on goat heads at the pool and came to us crying.
The KOA is a bit of a distance, about a 30 minute drive, from Lake Isabel and the Kern river.
The KOA has nice amenities free showers, pool, and breakfast in the morning (just bring your own mess kit).