We had a great time at Kostoula's apartment. Kostoula welcomed us with gifts and also gave us an additional one when we left. The apartment has a very nice view and is located in a small nice cretan village with lots of great restaurants.
The beaches Kostula adviced us were all safe but be careful if you try other ones, such as the Red beach near Matala. There, the current is very strong, and we were there, some people almost drown (there is no surveillance there). In any case, the area around Kostoula's place has a lot to offer with beautiful beaches and stunning landscape.