We stayed there in October. Nice clean rooms, but they were very humid. The view is of course astonishing.
This is supposedly "traditional cave houses" and yes they might be nice, but the rooms do have not such a great view... (ours didn't have any windows) the only great views you get are from the shared terasse.
Breakfast is OK, worth an average mark. Served quite romantically on the open terasse.
Staff was very friendly. We were on Santorini during an all-island power outage, and they were very caring and helpful.
Considering the prices of the surrounding hotels this is still a fair deal.