I would totally recommend staying at the Three Sister's Hotel. It is surely a very unique experience being able to stay in a Tulou and experiencing the local life in there.
Just be aware the building is mostly wood, which means that it can be noisy and the walls are thin. So if you are a light sleeper, I would suggest bringing some earplugs.
The inn keeper was also super friendly and helpful. Even though we didn't speak the same language, we could communicate easily through Wechat, and he gave me tips about the public transport I should take to go to my next destination.