So I want on a week long backpacking trip in June of 2017, right in the height of the heat wave in California. I spent a couple days in San Francisco before my trip, and unfortunately was naive in thinking my naturally tan self did not need sunscreen (I am from Indiana, and the sun is not nearly as close.) Anyways, I ended up with a second degree sunburn and severe heat exhaustion/stoke/whatever. I was so nauseous I was struggling to eat enough to sustain myself. After two nights in the backcountry and one night in the backpackers' camp, I had to accept I could not continue to solo backpack in my condition.
Camp 4 is first come, first serve. And I did not wake up early to get a campsite, completely unaware that the line gets incredibly long in the middle of the night. I was so very fortunate that I was the only solo camper, and received literally the last spot in the campground. So although I had no troubles getting a spot, I surpassed over 20+ people that morning who had been in line all night. My recommendations would be to get there very very early and plan to camp out in the line, especially if you have a larger group. Also, I would recommend going in the middle of the week, since more people are apt to be there on the weekends.
The campground itself was basic and sufficient. Each site holds 6 (or maybe it's 8 people, I forget) regardless of whether you know them or not. This was actually a benefit to my solo self, because I had people to talk to and I made some cool friendships. I had absolutely no issues with people messing with my stuff, even when I would leave it as I went on day hikes, of course never leave your valuables unattended just as a rule of thumb. The bathrooms were as you would suspect in a campground, not always the cleanest but definitely better than an outhouse! I did see housekeeping every day too. The water available was cold and refreshing and the shuttle stop was literally right across the street. The showers were a decent drive across the park, but again even without a car, the shuttle system is so easy to get everywhere and anywhere around the Valley.
This campground was definitely more than sufficient than my unexpected need. Although I would recommend trying to get a reservation at another campground if you are planning far enough ahead of time, that is purely because of the difficulty to get a site. It was a pleasant experience, and helped me recover and relax from my illness. The only thing I wish is that I had felt good enough to try bouldering on the boulders literally right beside the bathrooms, like much of the other climbers staying within the campground.