Perfect stay! Highly recommendable. The apartment is located centrally in the Heart of Besiktas, yet on a quiet road. It was super clean and with stylish furniture. The balcony is one of the highest up in the area and has a beautiful view. Our hosts were super helpful and kind - whenever needed, they responded quickly and had personal recommendations for restaurants etc. So were the neighbors e.g. from a Café beneath that we were fortunate enough to meet. An additional highlight was that the Apartment is located right around the corner of Besiktas' famous breakfast street (beşiktaş kahvaltıcılar sokağı), which offers all day Turkish breakfast/brunch. Besides, the ferry station 'Besiktas' is in 5-minute walking distance. From there, take a public ferry on beautiful Bosporus to the Station 'Eminönü' (for 15 TL currently) and you can walk to visit Hagia Sofia etc.
Besiktas itself is a lovely and lively place for eating, shopping, relaxing in the park, and going out and getting to know the hospitality of the turkish people. It is a great place to start exploring Istanbul, as commuting from here is easy by (cheap) taxis, busses, trams, ferries, or simply by foot. Enjoy you time at this apartment - we had a perfect time here!