Great camping, terrible access road
The SER campsites are beautiful and tranquil. We camped with friends at Goddess Grove, which had ample space for our tents, a lovely seating and hanging out area in the middle of the clearing, and felt very relaxing and enveloped by nature. The facilities (e.g. porta potty) worked fine and the main parameters of the camp (no fires, no potable water available onsite, pack all trash out with you etc) were well communicated by the hosts.
The one thing I wish I'd known more about in advance is the access road. Getting to the campsites requires about two miles of slow (5-10 mph) driving on a VERY rough, steep one-lane gravel road. There were a couple of slopes that took multiple tries to successfully ascend due to the steepness of the incline and the looseness/slipperiness of the gravel surface, and we saw other campers have the same difficulty.
The loose, rough gravel is actually a danger to your car's undercarriage if you don't have a 4x4 designed for off-road use. We got pebbles stuck in our brake rotors that made an awful screeching noise and we were worried our brakes and/or steering would get damaged. As it happens we managed to get them out without damage to the car, but it was an unsettling experience. I wish the listing had had a clearer warning about the quality of the road.