Mehmet's place is located very close to sultanahmet and is convenient is your wish to explore the old parts of Istanbul. All historic sites like Hagia Sophia, Blue Mosque are with-in 10 mins by foot.
Regarding, the apartment themselves, the room we was on the 3rd floor and is only accessable by stairs (This might be a problem if you have mobility issues). Other than transferring luggage during checkout we did not have any problem with the stairs. Mehmet was nice enough to help us transfer the luggage during check-in.
The only feed-back I like to give Mehmet regarding our stay is to provide some complementary snacks and beverage in the room. Since there is no breakfast offered at this place, It would help if you have these in the room to start the day.