Hikmet's apartment is a great place to stay in Istanbul. The apartment is clean and spacious. It is centrally located in walking distance to all of old town. It is easy to get on public transportation for trips further out. It can be a little noisy during the day as the apartment is in a shoemaking district, but at night and on the weekends, the apartment is very quite. The wifi is good.
The best part of Hikmet's place is Hikmet himself. As a host he is very helpful and inviting. He made us breakfast one morning and checked in a couple of times (we stayed there two weeks) to make sure everything was okay. Really great host.