I stayed at Pinar's for almost two months and had a good time. The studio itself is really nice and comfortable. As cute as you see in the pictures. I have no objections.
The hosts were always responsive and always willing to help when it was needed. Much appreciated.
The only thing I would like to mention is the location of the flat. It's very close to Istiklal, the heart of the city. However, it is deep inside Tarlabaşı, which is not the best area. It's totally fine during the day and when you walk home with more people, but if you are a woman traveling by yourself, you might feel unsafe at night.
As the neighborhood is not touristic, many taxi drivers will need good explanations (in Turkish) to find their way. Many will refuse to enter this neighborhood.
That being said, I generally felt ok in the neighborhood and did not have big issues. Thanks Pinar and Firat for being always reachable. Istanbul is the best!