I've been in Grandma's house for a week with other 5 people.
The house has plenty of space: 3 big rooms, 2 bathrooms, 1 living and 1 kitchen. It is a very quiet place, and it has a balcony with a GREAT view of the sea and of the famous Oia's sunset.
Everything was clean, and the house is in a good location, 2 minutes away from the center of Oia but in a secondary and quiet street.
Rodanthe was a great host, always ready to answer our questions and to give us advices about the island.