We absolutely loved the Soul Cave House! It's snug but perfect for the three of us - husband, self and teenage son. The location is pretty special, too, just off the main Oia drag and with a view of the glorious Caldera from the terrace. Maria was a great host: nothing was too much trouble. She sent a driver to meet us at the ferry port. She booked us a table at Kastro for a sunset dinner (highly recommended) and on a sunset catamaran trip the next day. And she drove our stuff to the hotel where we were spending our second night. (We needed a base with a pool until our evening ferry.).
The cave house itself was beautifully furnished and very comfortable. It was a rare treat to sleep in one of these original Oia houses.