Johanna's place is a perfect place if you are going solo and is close to everything in the city. Once you are used the public transportation, you would know how convenient Johanna's place is.
It is close to lots of restaurants and is in a safe neighborhood. I felt safe walking in the later part of evenings and the place is in the quieter part of the city
Johanna's was very helpful passing on information to me, right after I contacted her even before booking her place.
If you are traveling to Istanbul and wanted to something closer to - Blue Mosque, Hagia Sophia, Topkapi, Grand Bazaar etc, this is the place for you.
I would recommend this to anyone in a heat beat, and have a good time.