We enjoyed our stay overall - enough space for the 4 of us and the location is perfect - 5 minutes walk to Galata tower, 5 min - to Istiklal street, 30 minutes - to Sultanahmet. Coksun was very responsive and we appreciated the flexibility with check-in.
However, I wish the description stated the apartment is in the semi-basement, with windows at the ground level in the living room and no windows at all in downstairs bedrooms. Also, there is AC upstairs and in one of the bedrooms, but master bedroom did not have one and it was warmer than I would like.
Overall, the apartment is a goof value for a family if you know what to expect.