Me and my brother stayed at Aikaterini's apartmenmt for 5 nights.
The place is perfectly located, 5 minutes walking from Monastiraki metro station. The Acropolis and most touristic spots in Athens are within a walking distance.
The neighborhood is cool and hip, with street graffiti/art all over the place.
We also had a free access to the building's roof which has a stunning Acropolis view!
We arrived at the apartment in about 10pm, Aikaterini waited for us for a warm and friendly welcoming! She is a lovely lady, that helped us with everything we needed, including advises for our Athens trip.
If you are looking for a nice place to stay in central Athens, this is definately the place! Don't hesitate.