We enjoyed our stay at Behic's place. It is new, clean, and exactly like how it is in the pictures. Good amount of space for our family of 5, with 3 teenagers.
The location is awesome - 5 mins walk to Galata tower and the T1 line. The road is a bit steep, but not too bad. Good eateries nearby, but mostly catering to the tourist crowd.
Behic is easy to communicate with. We had a minor hiccup with a power surge, and he promptly sent someone to take care of it. There is a washer and dryer in the unit, so it is handy. It's a bit different from what you see in the US - some instructions on how to use it would be helpful.
Loved the place and would consider staying there again.