Two members of my family and I stayed here for 6 nights. Overall, it was a nice stay. The location is incredible: mere steps from Galata Tower, yet far enough away from the crowds that noise at night is not an issue. Accessing the unit requires climbing four flights of stairs.
The apartment itself is quite charming, with a lot of wood detailing to create a warm atmosphere. It's also big: three full-size bedrooms, a large kitchen, a large full bathroom, and one half bathroom. The one complaint that we had during our stay was just how dim the flat is at night, especially in the kitchen and bathroom. One small lightbulb is not enough to illuminate a room of 20 square meters. Another important thing to keep in mind when sharing the flat with others is that all the interior doors have fogged glass panes in them, which means that a person in one room may not be able to sleep (if they require darkness) without the other lights in the adjoining rooms to be switched off.
We never met Kardelen in person, but she is very communicative and punctual with all questions. That counts for a lot!