Great hosts with very friendly and welcoming attitude -- quick response to questions, exhaustive information about arrival/stay/leaving. And an extra-early check-in after night flight really saved me the first day of trip.
Flat is in brilliant location -- 100 meters from Syntagma square and metro station joining two metro lines, with direct metro connection to airport (X95 bus stop to/from airport is also right across the square), 300 meters from the Parliament. Building is situated at picturesque and very central (thus busy) pedestrian street, but the flat is located in the inner part of building and thus is surprisingly quiet, no street noise at all. The only minor minus is that there's no exciting view from windows :D but indeed no need in it, because the charming Athens should be walked and explored, not looked at from windows :D
Good supermarket (Bazaar) is in several minutes of walking. Right the corner is 24-h McDonalds which really helps those who prefer night life :D Try Greek Mac there!
The flat is clean and has all needed for comfortable stay, including iron, microwave oven, etc.
Overall, excellent experience. Ευχαριστω πολι, Christina and Adam! :)