Mustafa's flat is in an excellent location! When I come back to Istanbul I would definitely consider staying at his flat again, or definitely staying in Moda and Kadikoy. There are lovely bars, cafès, restaurants, patisseries...I initially thought it would be far away from the European side, where all the touristic attractions are, but no - in 20 mins with the boat ('vapour') you are on the other side, in Karaköy, Eminönü, etc.
Mustafa was super helpful and friendly! He helped me with the internet (which was suddenly not available in the room) that was important for my work, so that I was able to work both from my room and the living room. Every time I had a question or a need - he was there to help me.
I did not use the kitchen, but it appeared fully equipped, and excellent for preparing meals.
I fell in love with Midji, the cat, he is the real star of the apartment - and even though I thought of taking him away when he slept in my suitcase, I did not -and now I really miss him.