The sites are all very remote; no onsite rangers or anything like that. Beautiful walk in sites, no carts to haul gear so pack light! The sites are really near some stagnant water, though, so WAY too many mosquitoes, even with the really intense bug spray. We were there in mid-June on one of the hottest weekends of the year (planned about 2 months in advance and quite unexpected heat wave) and we were massacred the second we walked into the site.
I do believe these would be lovely sites in the fall or Spring, though.
Sandill Station is right outside Lake Mills, WI, right off the Glacial Drumlin bike trail. It features 15 campsites and 1 group campsite in an oak savanna, with varying degrees of shade. What makes this campground a bit different is that all 15 standard sites are carry-in only. The parking lot is anywhere from 100-500 yards from the campsite, depending on which one you choose. There isn't anywhere to buy firewood, so buy from a local resident/gas station. There are showers/flush toilets at the nearby Glacial Drumlin office in Lake Mills, but none on site, only pit toilets.
The campsite we were on was spacious, private, and beautiful. We had two large oak trees on either side of our site, giving us a good amount of mixed shade. We walked over to Mud Lake (in the park), and only saw sandhill cranes flying, not standing in the water. Also nearby is Aztalan State Park and Aztalan museum. The state park is beautiful grassland and prairie, and the Crawfish River flows along side the park. There are hiking trails as well as guide tour booklets. The museum has a small fee, but is a collection of Native American artifacts as well as things from local residents and their ancestors.
Overall, the campground is a nice choice if you want a private, quiet getaway into the oak savanna of southern Wisconsin. I wouldn't go in the middle of summer, due to the limited shade, but it was very nice in early fall.