I knew that my stay in Santorini would be amazing, and it became even more amazing because of Vivi and her apartment.
I never had any problems contacting Vivi and she always promptly responds to every email and every question I had. She picked me up from the airport and delivered me straight to her apartment (with the famous and very delicious welcome cake waiting for me).
The apartment is huge and the location is fantastic, just about 5 minutes walk to the main square of Fira and the centre of the village.
It was located in a quiet street which allows you to escape from all the activities in the centre of Fira. Given that it was the Christmas holiday period and a lot of the locals going on vacation, I did not find any problems finding everything I needed (from grocery, food, boat tickets, bus services, etc.). I guess, the house being in the centre of Fira is the reason for this.
I would definitely come back to Vivi's place the next time I am in Santorini.