You will love your stay. The apartment is located in a quiet neighborhood on a pedestrian-only street just a 12 minute walk to the south entrance of the Acropolis and about 7 minutes to the Monastiraki subway station (M3). The apartment had everything our family needed; a full kitchen that opened into a spacious studio living area. Then there were two bedrooms and a bathroom separated from the living area. Even a washing machine which we took advantage of.
Beyond the stay, you will be in good hands with Alexander. We talked a few times before we arrived, and he offered to store our bags for a few hours at a hotel he owns a few blocks away until the apartment was ready (15:00 check-in). He checked in with us during our stay to make sure we had everything we needed. And again, after we checked out, he stored our bags for a few hours until we caught the subway back to the airport (no cab is necessary...easy to get in to the apartment from the airport for 9 Euros per person).
I wish all AirBnB places were this nice and all AirBnB hosts were this communicative and generous.