My stay at Gökhans appartement was all in all pleasant. He himself is a friendly, helpful young man, who is always up for a chat and who wants to make your stay as nice as reasonable possible without intruding onto you.
The appartement is a lived-in-space, so it is not completly clean unlike the room you are staying in, which I had no complains about.
The location of the appartement is really, really good. The appartement is located on the asian side of Istanbul and literally just a corner away from the sea. A major ferry terminal as well as a metro station close by will open up the city for you. You can get tickets for the public transit there in addition to a variety of ATMs right next to the ferry terminal. There are also a lot of bars, cafes and small stores in the vincinity, that are open up until late.
Long story short, I would lodge with Gökhan again.