We had a great time at Plakoto house.
We were 6 friends of 20-25 years old. The house is 5-10 minutes car from the city of Apollonia and 10 minutes from most Sifnos beaches, so the position was not a problem in any way. For us, the house was just perfect: brand new, with 2 big bedrooms and a smaller one. The two bathrooms were clean and Margarita left some complimentary shampoos and bath soaps. The living room and the kitchen are very spacious and perfect for some chatting before going to bed while sipping some Raki or Ouzo ;)
The space around the house is huge and attractive with a nice garden, but unfortunately it was a windy week and the house is exposed, so we never could have an outdoor dinner.
Margarita and her husband were nice hosts. Don't worry if the communication from her is not very constant before your arrival: she has everything under control and she made sure that everything was alright during our stay. And it was.