My wife and I spent our honeymoon here at the Mermaid House. It was exactly what we wanted: clean, quiet, and peaceful.
Sadie, was very responsive to our questions before we arrived and while we were there. She also checked with us to see if we needed anything.
The house is tucked away on a dirt road on the west side of the island. It's a short walk to the beach to enjoy a beautiful sunset. You will need a car when staying here. The town, restaurants, and beaches to swim at are on the other side of the island.
I would recommend staying here to anyone visiting Block Island.