I stayed in Sinan's place for 1 month in January. The place is beautifully located right next to gorgeous view on Bosphorus. The block itself is very very quiet and peaceful. A lot of shops nearby, one of big ones working until 23:00 which is a rare occasion in Turkey. 24/7 small ones are also available. Bus stops in a walking distance. Authentic bazaar every Wednesday.
Some people are afraid of Mosque sounds, this place has no such a problem, sounds are distant.
The flat inside is quite big, has everything you need and in good working condition. Amazing view from balcony. It was warm also in coldest winter time in Istanbul. Only minor concern was a weak, almost broken fridge door, but it still does the job...
Sinan, the host himself is a very welcoming person, he speaks perfect English and always keeps in touch if needed. He can provide you wide variety of check in/out options, valuable advices and just a friendly company and conversation.
Overall impression is 9.5/10