I spent three months in Berat's apartment and he really is the best host you could wish for.
He was always available, super friendly, replied fast and always had a solution for my queries. He also showed me a little bit around in Istanbul what was super fun and even organised some plants for the flat! He also provided me with super helpful tips.
The flat is simple but equipped with everything you need. The bed is super comfy and there is plenty of space in the living room.
The location is nearly perfect: Two minutes to Taksim Place/Istiklal Street (also Metrostation) and 6 Minutes to the Tram which brings you directly to the touristic places in Sultanahmed (Hagia Sophia, Blue Mosque etc).
I can highly recommend this flat, except if you are a noise-sensitive person since it is quite noisy in the bedroom (you hear the pidgeons, seagulls and the discos, but the latter only until 1 am).
Have fun in Istanbul!