Very close to Hagia Sophia and Blue Mosque by foot. If you want to go to Eminönu/Sirkeci, take a bus from Kumkapi. In Kumkapi (3 blocks away) is also one of the liveliest places to dine and enjoy live local music.
The apartment is more than fully equipped with a big shower, balcony is small and not so safe and clean.
If you want to have clean towels, you should ask Şaban.