Without question the best Airbnb I have stayed at. For one, the apartment itself was beautiful and in a fantastic location. There is a huge veranda that overlooks a quiet street and has a view of the acropolis. The air conditioner is very strong and cools the whole house, and there is even another one in the bedroom. This is an unusual luxury in Greece, where electricity is very expensive.
In addition to the apartment's features, Efthimis is a spectacular host. He was at the apartment within minutes after I messaged him that I had arrived. He was very communicative throughout my stay, but not in a way that was overbearing at all. His apartment was spotlessly clean and had every amenity you could want. He even went to a store and bought me an adapter for my American electronics after I told him I had lost mine (the adapter is now in the apartment for other guests). Furthermore, Efthimis provided a lot of information about how to navigate Athens. I have been to the city many times and am not unfamiliar with the neighborhood, and I still found his suggestions very helpful.
In summary, Efthimis has a great apartment and clearly takes pride in being the best host he can be. I will definitely check for his apartment first the next time I am in Athens.