Mehmet is a fantastic host. He responded to all questions in a really timely manner and even helped me with a few issues I had around Istanbul. He even called a hospital for me and tried to get a COVID test scheduled before I left. We had coffee together when I arrived and again before I left, which was a really lovely touch with good conversation. He upgraded the internet for me when I needed it for my work ... they leave nothing to be desired.
The apartment is exactly like it looks and in a stellar location - easy to get to buses, taxis, and to Taksim and Eminonu (where the Blue Mosque, Hagia Sofia and Grand Bazaar are. You can walk to Eminonu or take a bus very easily).
The room was cozy and comfortable and had everything I needed. The absolutely only downside is that, being down low, it really doesn't get any natural light and always feels like early or late evening from inside ... but if you're going to be out exploring Balat and Istanbul, that probably won't bother you much. I'd recommend it!