Osman was our host for 4 days and all i can say is that we had an amazing stay there. Osman was very helpful and arranged a comfortable private taxi transfer for us to the airport and back, at a very reasonable price.
The apartment can easily accomodate 4 persons and has all the amenities. The location of the apartment is super and you can be in the city center on a short walk. The views from the apartment are spectacular overlooking the city.
All in all if you are looking for a place to stay in Instanbul Osman's place is a great choice