We had a very nice stay at Katharina's apartment. She was very nice and helpful as a host and great to keep in touch with. Even though the apartment is located right by a busy street, you can barely tell thanks to the well-isolated windows.
The nearest metro station ("Kerameikos") is in walking distance (about 10min) and surrounded by multiple bars and clubs for those who want to get the most out of Athen's night life. We would recommend the apartment anytime.