Great location, a very cosy and charming apartment, comfortable and authentic. I had a great 2 days in Istambul, and this is the best area to stay.
I stayed at this apt. at the 2nd flore, maybe if you choose the upper floors of Defne's house you may avoid hearing people climbing up the stairs at night or early morning. I could hear them pretty well on Friday night and they were a bit noisy. But this is not a big problem anyway.
the apartment is equipped with all the necessary staff similar to a hotel. All in all it was great, thanks to Defne.