We had a fantastic stay in Greg's apartment. It is clean, modern, functional and comfortable. the check in and check out process was very easy.
The location is fantastic, with a number of great restaurants and bars within 10 minutes walk. The apartment is also roughly a 30 minute walk from the various sites in Athens (such as the Acropolis, Agora and Acropolis Museum).
The apartment was very cool with shutters to keep the temperature down and had a couple of great showers.
I'd really recommend staying here!