We stopped here in August 2020 to do a day of river tubing on the Au Sable. Stayed two nights with my family (2 adults, 4 kids) Nothing too amazing or too bad about the park. It's fairly hilly so be aware of that, and it's a bit of a walk down to the lake. However, the highlight for us was snagging a picnic site down at the lake and setting up our hammocks by the beach for the entire afternoon. The kids played in the shallow water and the adults sat in the hammocks and relaxed.
Facilities were fine, clean bathrooms and showers. Nothing fancy but it's a state park so that's the norm.