This is a great apartment in Cihangir, one of the best areas of Istanbul, a Bohemian-like neighbourhood popular with artists, journalists and expats. It's 3-5 minutes walk from several nice cafes and restaurants and 7-10 minutes from a row of antique shops (on the back alleys that go towards Galata).
The apartment (a duplex) itself is clean, quiet and functional with three large double-bedrooms (the master and another one are on the living room level and one bedroom on the second floor) but only one toilet/shower on the first floor. The owners (or the guys who run it) are very responsive and friendly. The flat is on the 4th floor of a building where there seems to be other Airbnbs (possibly managed by the same team). We were there in November and the heating was perfect.
All kitchen equipment worked perfectly. There is an occasional hint of sewage smell in the toilet/shower which is a feature of that part of Istanbul (not the building). Apart from the master bedroom, the other two don't have wardrobes (only coat rails and hangers) which would have made the rooms lovelier and more practical. The TV has only Turkish channels (including one in English that is TRT World). The flat can benefit from a satellite receiver for its international guests.
The building is on the corner of a street with a steep slope, again a feature of Cihangir, and being located in a back street, is much quieter than the centre of Cihangir which is only a few minutes walk away. We would definitely go back to this place.