The apartment has a soul. It is housed in an old building, but is extremely well-kept and cozy. I spent two months there and I can honestly say that I felt at home.
A big advantage is the large number of shops and restaurants nearby. Opposite the building is a bakery. Plus the proximity to the subway (10 minutes to Şişhane, 15 minutes to Taksim).
The only drawbacks I noticed were that there were too few hotplates - during a long stay it is difficult to prepare a meal on one. And the temperature of the water in the shower. Although the heater heats the water, the shower may surprise you and let the water run warm once, then change to cold, and so on and so forth.
As for the owner - a very kind man. He takes care of the apartment and tourists. He responds very quickly and helps if there are problems.
I highly recommend this place!