Overall, I had an enjoyable stay at Saban's place. The apartment is perfectly located in Sultanahmet on a quiet street and is walkable from many attractions and restaurants. And Saban helped arrange the airport transfer to and from IST.
While in Istanbul, Saban's friend Yavuk helped with check in and answered questions. He was ten minutes away in case I needed anything and helped coordinate cleaning during our stay. He was great.
However, prior to our stay, we did have some challenges communicating with Saban. I had to send multiple messages to get questions answered and often waited days for a response. I wasn't sure if I'd be able to check in early until I arrived, despite inquiring ahead (they do have luggage drop off though.
Also, I know this is out of the host's hands but the walls between the apartments in the building (I believe there are 4 airbnbs) are very thin, and you can hear your neighbors and vice versa. Depending on who is staying near the, this may be a disruptive experience.