Mustafa is really nice and helpful person. The accommodation gone good. The flat has a central location near Taksim square, Cihangir, Istiklal street, bus and tramway station till Sultan Ahmed area.
But you need to pay attention that house is located on the sloping streets and it makes it difficult to get there with luggage without taxi. Also flat is on the 3th floor without elevator, the stairs are steep. Otherwise, everything is fine :)