A memorable and enjoyable experience. 5 star apartment, 5 star management. Top of the line materials throughout the apartment, except maybe the couch and it's not bad just doesn't meet the level set by other elements.
Some practicality was sacrificed at the expense of luxury... But the feeling of luxury is so high you probably won't mind. And you'll appreciate the thoughtfulness in the little things to make your stay as pleasant as possible.
Comparable to top class suites in world class 5 star hotels - but with a lot more stairs to get in than you would like. However that's a common trait for apartments in that part of Istanbul and you get used to it. Besides the apartment is so nice it makes you not want to be out as much anyway.
I miss that place already, it is a standout among standouts of airbnb stays.