I have stayed in this flat for 15 days and here is my feeling about the place.
Host:
Memet waited for me for check in and helped me to carry the luggage with stairs. He is a gregarious, flexible and generous man and helped me whenever I needed something during my stay. He speaks English very well so you won't have any issues with communication.
Neighbourhood:
Beşiktaş is a lively neighbourhood with a great night life. The flat is located near cafes and pubs and you can find anything you want by walking few minutes.
Flat:
It's located in the second floor and there is no lift (This is the case for most of buildings in Istanbul). It has got windows in the two sides of the building and would have quite a bit of sunlight throughout the day. The flat is well equipped.