If you are on Sifnos, then this place would be the best place to stay!! It’s located in the beautiful, historic Kastro with picturesque white houses and narrow streets! The cute cafes and restaurants were closed at the time we have been there (off season, end Oct) but you can reach everything you need quickly in the town nearby (in case you are coming off season too :-)). We recommend renting a car and also try the different beautiful hikes in the south of the island (reachable in 15 min by car :-)).
The apartment itself is very good equipped, stylish and the Terrasse is just beautiful (magical sunrises included :-)).