I want to start by saying that Sophia herself is very kind and well-meaning host. She picked us up from the the ferry and is indeed very kind.
Travellers to this location should know that it is very, very remote and a car with 4 wheel drive and high off the ground (ex. a Jeep) is 100% required if you'd like to stay here. The location is down a 2km cliff/dirt road this is inaccessible without a car. In our experience, car rentals would not rent to us without an international license and/or also because of the rough terrain of the location would not give us a car. Note to travellers outside the EU: you need an international drivers license to rent in Sifnos. The road down is very very rough. As well, this location does not have wifi or cell-service - there is only cell service on the road, 2km up. In addition, taxi's will no go down the road, they will only drop you at the top of the road and you will have to walk down the dirt road *keep in mind if going out at night. The next closest town to get food/restaurants is about a 25minute drive.
Sifnos is a beautiful island with amazing food and this particular beaches water is very beautiful. The house itself is clean and well kept, however the location is VERY remote so keep the above in mind when planning your stay.