Osman's apartment has an absolutely fantastic view of the city, especially Galata tower and the moon at night. It's a 5 minute walk down a steep hill to the Tophone tram stop but you'll see that steep hills are the norm in Istanbul. Be aware that the apartment is on the 4th floor and there is no elevator.
The proximity to the tram makes this a great place to stay, it's very quick and easy to get into the historic center of the city, and there are a lot of great restaurants across the street from the Tophone tram stop.
I highly recommend staying here, the view is definitely worth all the steps