I had the pleasure of being the first guest at this Airbnb and stayed for just under three weeks.
The apartment itself is stylish and comfortable and located very well, less than 10 minutes walk to İstiklal, and close to all Beyoğlu attractions but in a quiet residential area. Mustafa and Bariş provide all the basics for living like you're at home and their communication is excellent. I would absolutely stay here again and did actually extend my stay.
**Note: the apartment is on the 3rd floor with no elevator and the building is at the bottom of the Tepebası hill, so it's not a good option for people with limited mobility.