We stayed at Yusuf's place for three nights in May. And I can tell you that it was amazing !
The location is really great : you can walk to the main monuments of Istabul (Blue Mosque, Topkapi Palace, Hagia Sophia...). If you want a quiet room in the heart of the historical city don't look further, you have found the perfect place !
The room itself was really nice, with a comfy bed and a little kitchen. You can also find a nice jacuzzi in the bathroom. Also the room is cleaned everyday !
Yusuf, the host is a great guy, he gave us good advices about the city, called a taxi for us, and if you are lucky enough you could share a coffee or a team with him.
Long story short, this place was amazing and I recommend it to anyone who want to discover the beautiful city of Istanbul !