Stayed at an RV site in early June, 2021.  The site assigned to us was on the outer loop and directly opposite Devil's Tower.  The tower was nicely framed by a pair of trees at our campsite.  The entrance to national park is immediately next to this KOA.

The hosts were friendly and accommodating.  No complaints with the water and electric service at our campsite.  Our site (as were all the others as far as we could tell) was level.

The restrooms were clean, but like things seeing a lot of use these days needed a couple repairs but nothing major.   The on-site showers were also clean and the water warm.  The KOA staff watered an adjacent site through the night while we were there.

Note: site's were available on first-come basis at nearby Devil's Tower Belle Fourche campground but don't offer the amenities of the KOA.