It was a really nice stay - the hosts were friendly, easy to reach and responsive. The place has central location, walkable to the main sight seeing in Karaköy and Eminönü. When we had some minor issues, they were immediately solved. Definitely recommend to stay !
The only one thing you should keep in mind is that it is a mansard flat so there is limited space between bed and ceiling, it might be problematic for tall people.