Unfortunately the bungalow 202, which we had booked in Sonai was very smelly so it was not acceptable for us to stay there for the 4 nights we booked. In general the Mumbu Sonai branch is pretty run down and heavily overpriced for what it has to offer.
I have to say though that the staff was really helpful, especially Ayumi (arigato gozaimasu), trying to find alternatives during peak season which resulted in us staying in 4 different places for the 4 nights we spent on the island, which was ok for us. The alternative rooms were all fine, especially the ones at the other 2 Mumbu locations with very modern container rooms.