I echo the other rave reviews of this apartment for a convenient stay in Athens. The flat was modern, clean, and quiet while being located just a short walk from the town center (10 minutes to the Acropolis, 15 minutes or so to the Plaka area, National Gardens, etc.). The nearby Filopappou Hill provides a lovely spot for hiking/climbing and splendid views of the city.
There isn't much in the immediate neighborhood except a bakery across the street, but that's why it's quiet at night, and there are small grocery stores just up the street for basic necessities.
As for our host, we couldn't have asked for more. Maria was extremely friendly, responded almost immediately to any inquiries, and provided lots of useful information about the area. In the flat there were pots, pans, and dishes for cooking and eating, including everything you'd need to make tea or coffee. The cell phone they provided was another useful bonus and there was even a bottle of wine on our arrival! Maria's husband, Costas, met us at the flat and both he and Maria certainly made us feel welcome. Overall, we couldn't be happier with our stay.

Just a quick tip: in Greece, we learned they conserve energy by turning off the boiler at the electric panel on the wall (outside the bathroom door in the hallway). Don't forget to switch it on before you need hot water, then switch it off again.