I liked this place quite a bit. It is close enough to a lot of attractions to easily get around on foot or public transit, but far enough away so as to not be in the thick of things. There are two grocery stores and a bakery within one block, and several restaurants nearby.
The apartment was quite nice, in an old-fashioned style that I really like, sort of like what you'd see when you visited your grandma's cool friend who was a widow and smoked Virginia Slims and talked about going yachting in the summer with the Kennedy family. If you snore badly, as I do, the couches in the second room both fold into a bed and you can spare your wife being awakened by a chainsaw.
The staff members were all very nice and spoke English quite well. The owner was quite attentive: I never met him in person, but he answered my messages immediately and had his staff help me.
Finally, the breakfast is small but good. It is a nice way to not be famished when you go out, or you can order more at the cafe (the prices are very reasonable). All in all, I would happily stay here again next time I'm in Istanbul.