We stayed 4 days at this apartment. It is an excellent location, 3 minute walk to the metro. You can walk to several sites within 15 minutes or so if you like.
The apartment was very clean, well equipped kitchen, and had a lot of nice little touches to make you feel at home.
The outdoor terrace was a great spot to sit out and have breakfast, tea or a beer.
It is on the 4th floor and no elevator so you must be okay with the stairs, which we were.
I would recommend this apartment to stay in while in Athens.