From before we went - questions about classes, transportation, and about the neighborhood itself - through our last night there, the place and the owners were responsive and helpful. We had one emergency, an illness, and Eleni went to the pharmacy, picked up the meds, and came by on her motorbike to make the delivery.
When we needed them, they were there; when we did not need them, they kept a respectful distance. This place, these people, and the location w/in the Exarchia neighborhood are the finest combination of elements Airbnb offers (and over the years I've stayed in many, many Airbnb's).
If you have the good fortune to reserve Sotiris's place, snap it up!