Our stay was great, we enjoyed the morning and evening on the balcony and the stunning view - which is even better in person than in photos. I would definitely go back. Besides these feedback points, our experience in the apartment has been amazing and we actually miss it, and regret not having been able to spend more time.
The only thing to keep in mind is that the apartment is at the 4 floor with no elevator, which is not unusual in Istanbul for an historical building, but good to know in advance.