The apartment is quite clean and light. It is situated just near Hagia Sophia and Sultanahmet (about 10 minutes walk), but be sure that you have comfortable shoes, because Istanbul is on the hills and you need to go up and down a lot :)
Also, there are a lot of places to eat nearby. And Ahmet is a super host! He’s very kind and responsive, so you won’t have any problems and he’ll answer all of your questions.