Safa is a great hoster and the apartment is very well located. He contacted me almost 1 week before, in order to agree on my arrival. However, wifi connection was really bad. He also gave us a different apartment to the one booked for the first two days of our stay (he said he thought the one he gave us would be more confortable, but it wasn't. It had no natural light, only one small window and bad maintained). He gave us later the apartment we actually booked and it was really ok, except for the internet.
It's ultimately a nice place to stay in Istanbul and Safa is a kind person.