I stayed in Istanbul for 5 days and Mert's apartment was just perfect to stay in. The location is close to amusement park and it's quite easy to get to the city center from there. I really liked the atmosphere and design of the apartment as well. It was clean, cosy and comfortable. The area itself is very safe and calm. I recommend you to stay in asian part of the city, Bahdad Caddesi which is very close to Mert's apartment. I felt myself like home there :)