I stayed in this apartment for 3 nights. To start with, the neighborhood was really not good. Honestly one of the worst I've ever seen. Most people couldn't speak Greek, at most they spoke some broken English. Mostly I heard Arab.
I frequently heard the police and the first night I saw somebody was damaging a strangers motorcycle on purpose. Later someone tried to steal a womans phone about 20m away from my door. As I ran downstairs to check for her, one guy got it back for her so she was fine.
The third day they broke into my car and stole stuff which was hidden in the trunk.
The owner can not do anything about the location so they are not to blame here.
The apartment was also not well equipped. For example only one fork and two knifes or so. No sponge or anything for cleaning the dishes.
The apartment itself was clean and you could see the acropolis from the balcony.
If one is careful and knows about the location, they should be ok but it's important be informed about it before.