Eray's place is as described, and I had a lovely stay. It is a small apartment on the top floor (4th floor walkup) of a building on a small side street on the border of Cihangir neighborhood. The address does not show up correctly on the AirBnB map, so it is very important to communicate with him upon your arrival to find the exact location.
He keeps the apartment very clean and gave me a useful orientation to the room, bathroom, and shared space when I arrived. I did not spend much time in the apartment, because I was too busy exploring Istanbul, but I enjoyed conversation and a drink with Eray each evening when I got home. The street itself is small (Ilyas Celebi Sokak) and there isn't much happening on it, but it is only a few blocks from many sweet cafes/restaurants and a short walk to the Tophane tram stop.
Eray lives in the flat and you will share bathroom, living room, and kitchen with him. All spaces are impeccably clean and living room is nicely designed. Bathroom has a free shower head in space and is not a stand alone shower stall.
I had a very early flight out on my final morning, and Eray called ahead to book a taxi for me in Turkish. The pick up was smooth at 5 am and I was very grateful especially because the road was closed for some construction that day.
Eray clearly enjoys meeting those who are traveling to Istanbul and stay at his place. He's kind and has a big heart.