Let me start with the basics: Mehmet's place is well located in the Sultanahmet area, approximately a five minute walk from the Blue Mosque and the Hagia Sophia, and about an eight minute walk from the tram station. The room is nice and spacious, and the wifi works great. A good selection of restaurants, all of them open late, are located nearby.
That having been said, if I could give Mehmet more than five stars, I definitely would. Here's why: I called Mehmet in the middle of the night, at around 1:30 a.m., on the fourth night of my stay, panicked because I thought I had gotten my key stuck in the front door. He was so nice to call a locksmith, who, when he arrived, took a look at the key and took it out... by turning it horizontally and pulling it out.
Incredible embarrassment aside (in my defense, I was sleep-deprived from the time changes so I wasn't thinking clearly - I had had no trouble with this simple task the past three days, so I don't know what caused this mental hiccup), Mehmet was very understanding about the whole thing. When I saw him the next day to apologize, he told me not to worry - that we are only human, and that we all make mistakes. Considering that I had disturbed his sleep in the middle of the night, and that he took it all in such good humor, I do say that I am very happy with Mehmet's hospitality, and that I highly recommend staying here!