Berker's place is just as others have described : Cool host, beautiful view, cozy and comfortable apartment, great location for the central historic part of Istanbul, and (other than the loud muezzin calls a few times a day) very quiet and peaceful. Communication with Berker was excellent, both before and during my stay.
His apartment was my base in Istanbul for over a week and I very much enjoyed my stay here. Also got a fair workout each day with the spiral stair climb up to the 4th floor as the vintage building has no elevator! I found the location was ideal for getting a taste of a local neighborhood in the heart of Istanbul yet not far from shopping, transportation, and major sites in this part of the city.