The hosts (Ioanna and her husband(?)) were very kind: They waited for us even though our ferry was 1.5 hours late and they suggested a late check-out on our last day, so we could sleep in and enjoy a full day in Oía without having to drag our luggage along.
The location of the little cave house is amazing - it's above Ammoudy bay, very close to the castle, but not directly on one of the busy paths, so it's possible to sit outside and enjoy yourself without having masses of tourists walk by all the time.
Internal decoration in plain, the blue-tiled bathroom is definitely the highlight.