I have been staying in airBnB in most of my travels and I would have to say that the overall experience of staying at Toni's apartment tops my list. Toni and his team was very responsive at the moment you book the place, they provided detailed information about the apartment and were very prompt in replies. I also appreciated the flexibility on check-in and responding to some requests. The apartment is exactly how it looked like in the photos and the video, which was totally superb in cleanliness, space and amenities. It's like staying in a service apartment. The location is excellent, the apartment is strategically located that allows the guests to walk to most tourist spots, restaurants and bars.
The only thing I will recommend is to provide the guests with at least two sets of house keys, given that it is likely the apartment will have more than 2 guests it is efficient to have two sets of keys so as to make the access more flexible to the guests.
Net, I highly recommend Toni's apartment for a very pleasant stay in Athens.