in one word, Bilal is a superb host. He is responsible, kind, and friendly. Thanks to him we checked in much earlier. The flat is nice and tidy and exactly like the pictures. the flat is located in a very strategic area for tourists. it is three minute walk from the Istiklal Cadesi (a bit uphill) and sishane metro station. and also if you go downhill, in four minutes you will be in Karakoy (highly recommend to visit). there are a few cafés and supermarkets around and you can always use online shopping stores (like Getir) to buy essentials (don't drink tap water in Istanbul).
so all in all this place is a must stay and I can claim that I have a very good friend in Istanbul.