This was a really nice campground. Very family friendly, lots of kids running around. Not very much privacy at all between the sites, but what do you expect at a busy place like Custer State Park? The bathrooms were very clean, and had showers with hot water. The showers are free of charge, and each time I used them the water was always plenty hot.
We stayed in site 2E, and it was a nice site. Extremely flat and level. It does have a trail running next to it, so all the visitors will be walking a few feet away from your tent/camper all day and night going to the bathroom.
T-Mobile cell service was pretty much non-existent, with no 5G signal at all, and only a sporadic 1 bar of LTE signal. I was able to make a phone call, but it kept dropping out every 10-15 seconds. Starlink worked great from this site, with a moderately clear view of the sky.