We stayed at Tunahan's flat for 13 nights.
We had a great experience right from the start. Tunahan was very responsive as soon as we landed - he and his friend helped us with our luggage (GPS shows the address a couple of blocks away, which is where our driver dopped us off).
Tunahan provided everything we need the first night, including standing in line, ordering the food we requested and delivering it to us.
There were a few minor issues in the house (e.g., shower head not being properly secured in place) and Tunahan addressed them promptly.
The flat was remodeled and very clean.
It was our first trip to Istanbul, and we were a bit nervous about what experience we will get from our AirBnB (would the actual flat match the pictures on AirBnB, etc...). Tunahan made sure we did not have much to worry about.
Finally, the house's location was very good. It was very close to the boat/transportation to the European side. It also had a great bakery and breakfast place (among other shops) in walking distance.
I highly recommend this place, and Tunahan as a host.