We just spent 4 Days in Istanbul and we really loved the apartment! It was really modern and stylish. It is very centrally located in the Fathi district, from where you can visit the blue mosque in around 10 minutes. The neighborhood was quiet and you could get a good feel of local Istanbul.
Yusuf and his team were really good hosts and would take good care of us. If you feel like going to a sauna and hamam after a long day walking through the city, you can just use the private sauna and hamam, which is really nice if you don't feel like going out again.

Should I find myself in Istanbul again, I would not hesitate to stay at this apartment again.