We (me and my wife) enjoyed the apartment very much. Very clean, with lots of convenient and practical details to make your stay comfortable. All knives are sharp, towels, tissues, toilet paper, detergent, shampoo, soap, dishes - literally all things, including electronics, that you need in your normal life - are available and functional.
The location is not in a touristic place. But food shops, street cafes, and a metro station - are there. If you speak even little Turkish - you will easily communicate with local people. If you do not know Turkish, you can point your finger at what you want to buy. The sellers can show the price on calculator.
If you want a fashionable and modern location, with luxirious cafes, then this place is not for you. The street where we stayed is a bit dirty, like many other streets in Istanbul. To us it was a little of shock, as we had thought that Turkey is a very modern and developed state. But after a day or two you get used to that. To our surprise many of the shops close very late: at ~ 10 PM or even later. So if you arrive late from a walk, you can still buy something around.
What we liked a lot - is communication with local people. Most are very friendly and try to help you: they try to undertsand what you say and give proper answers, explanations.
As to the apartment - as I said, it fully satisfied our needs and exceeded our expectations by lot. The owner is very friendly and always online to help you. He also pays a lot of attention to details.
Overall, our rating to this apartment = 110% out of 100%. The location: 75-80% out of 100%.