I had a great six-night stay at Stefanie's apartment. For one person or even a couple, the apartment is a perfect size and has all the necessities. The sofa bed is large and comfortable, while the balcony also provides a great spot for breakfast etc. There is a well-equipped kitchen for preparing food as well. A main highlight for me was the neighbourhood - it's close to the Acropolis and historical centre, while also having a slightly calmer atmosphere - that said, there are countless restaurants, bars and coffee houses right outside the door.
I wouldn't hesitate to recommend Stefanie's apartment to anyone staying in Athens!