We camped for 2 nights at the Mill Lake Rustic cabins inside Waterloo State Recreation Area. The area was really natural, lots of trees, dirt roads. You definitely need to make sure that you are prepared. There was a water pump within walking distance of the cabin. There was a vault toilet, which I found was not cleaned, lots of flies and spiderwebs everywhere. I sprayed for bugs, lysol wiped, and swept in there myself to make sure that it was clean enough for my family. The cabin was clean, had lots if screened windows, and the beds were actually pretty comfortable. We brought an air mattress that we ended up not even using. There are lots of electric heaters built in and we stayed warm at night. Plenty of outlets conveniently placed. We brought a mini fridge and were able to power up all our phones (which we did have good service on there), and electronic cookers. The cabin was well lit, with plenty of room to accommodate our family of 6. Mill lake was accessible on foot via a short trail walk. The cabins didn't have a view of the lake though. The Discovery center was a short drive away and the kids loved it. There were no showers at the Mill Lake cabins, you can go to the Sugarloaf campground to shower at a cost of $5 per person. There were lots of trails to walk. If you have a boat there is a boat access for Mill lake. We let the kids fish from the shore. They enjoyed watching the little minnows and butterflies around the marshy shoreline.
I think if we camp at Waterloo again I would like to be near modern bathrooms and a shower, because we have 4 kids. Ii did like the natural wooded area that were at though. It didn't feel like we were too close to lots of other people, or like it was a parking lot. The local DNR was friendly and helpful, and didn't bother us. It was a good experience overall; we will be camping at Waterloo again next year in a different camping area.