We had a lovely stay in Istanbul at Erdem's duplex apartment. The apartment consists for 2 separate units with separate bathrooms which was ideal for us as we were 2 couples. The house was super clean and had everything we needed. It is at a 5 min walk from Galata tower which is very convenient. There are a lot of nice cafes close by too.
Erdem was a great host. He helped us with early checkin and also helped stored our luggage on the last since our flight was in the evening. Would definitely recommend this place to anyone wanting to stay in the heart of Istanbul!