I had a fantastic stay at Ahmet's place on my recent travels. The location is central and with easy access (~ 10 min walk) to the ferries into other parts of Istanbul.
The place is large and with a great patio area (sometimes you will find a cat relaxing in a chair).
I rarely used the kitchen appliances but there are supplies present and at your convenience.
The slight draw back was the tiny shower space I used. But everything else was simply wonderful.
A note for future guests: the apartment is located on a lower level, and the window on the street-facing side has no privacy if the curtains are open.
Also, it is a noisy location because it is surrounded by all these great restaurants and bars. So if you are using this location to work from home or try and sleep in, this is not ideal for you.
Overall, I highly recommend this place to those seeking adventures in Istanbul/ Kadiköy. Ahmet is an amazing host!