We stayed for two nights, and enjoyed our stay for the most part. But our main reason to be there was to visit nearby Pictured rocks national lakeshore.
Otter lake itself is nice, and picturesque, i wish we'd had time to use our canoe to explore it, or even to take advantage of the beach. The grounds are full of trees and the sites are all shady.
 the owners are friendly, and it is very family oriented, kids everywhere. Although it's miles out of town, there is a nearby restaurant at Buckhorn resort. The camp store is rather minimal, and you can't get ice after it closes, so watch your cooler ( we didn't).
All in all, it's a very pretty getaway and I'd normally give it 4 stars except that we were staying in the rustic sites, and the is only one restroom. it's large and clean, but it's like 3 city blocks away. There's really no excuse not to have a couple porta-johns near those sites, especially since half of them have a view of a large shipping container in the overflow parking anyway.