One word - perfection.
The apartment was clean, spacious, with a lot of sunlight in the morning. We had everything we needed - hot water, coffee, tea, towels, toilet paper, blankets, basically everything.
Our host, Konstantinos is just a wonderful human being, and a professional. He arranged a taxi for us from and to the airport. Gave us recommendations for food, drinks and sightseeing, and was super responsive for everything we asked him.
The neighborhood is nice and close to the city centre, about 10-15 mins of walking. There is a metro station nearby, cafe bars, restaurants...
If we come back to Athens we are definitely booking this apartment again.