Everything was absolutelly perfect. This is really a place to stay when you visit Athens. The location could not have been better, we didn't have to take metro even once. Everything is in a walking distance. The apartment is newly renovated and it has everything you could need. Stelios was very nice. He met us at the metro station when we arrived from the airport and took us to the flat, which is just 3min away from Monastiraki station. He also gave us some useful tips.
The only problem that one could have with staying in this place is that it might be quite loud early in the morning, but for us it was not a problem.