The campground wasn't that special, but it was relatively inexpensive. There was shade at our site and it was walking distance to Wall Drug. The hosts (work campers)were friendly. But as per other reviews, there appears to be little investment in this park. Laundry facilities were average price $1.50 wash, dryers 25c per 6 mins. The playground equipment is rusted and a liability. We did not use the pool. We stayed 3 nights while we explored Badlands National Park.
One word - Expensive - even for a KOA! There's a great opportunity for a budget campground in Billings! All campgrounds seem to be expensive here, so we chose the KOA as we were members and get a bit of a discount. Seriously though you do feel like you are being gouged. The Wi-Fi is free but has download limits. We paid $42 (with 10% discount) for a basic pull through gravel pad (which shifted level overnight) with electric and water - no sewer. The BBQ and Breakfast offered appeared to be no bargain either. They seemed the same price as what you could get at the average family diner. Breakfast $7 Steak dinner $16. This KOA is the original KOA, they maintain it well - there are lots of staff (which is probably where the fees go), there are decent amenities and some good ones for kids - playgrounds, pool mini golf - but nothing very special to other campgrounds around the country to justify the price. It's not even as if it is a major tourist locale? If we didn't have to stay a few nights in Billings we probably would have moved on.
We stayed three nights here as a base to explore the region. Price was excellent (Good Sam discount). Hosts were friendly. Laundry facilities were good (honor system). We used a full hook up pull through site, which was level and some grass and a tree for shade. Neighbors were about average distance away. It was a bit out of town, but that was fine with us. The office has some basic perishables, and there is a chuckwagon restaurant next door (though we didn't have time to try it). It was quiet, and gave us a few less miles to drive towards the tourist areas.