We had a great stay at Kerem's place.
It is in walking distance to the Taksim square from where you can easily take a taxi to other sights or just walk through the Istiklal avenue towards the Galata square.
Kerem was very helpful and gave us a map and great restaurant recommendations. The room was very clean and was cleaned every day. The apartment is in a quiet neighborhood and has a nice balcony. We would definitely stay there again!