I will start off by saying that Josef's accommodation was one of the nicest ones that I have experienced with Airbnb. Outside of one concern that arose right before check-in, it would be a solid 5/5 in every aspect.
Josef was very friendly and provided a lot of information prior to our check-in. With the check-in process, one of his colleagues is there to make final arrangements and greet guests. This necessitated an additional cost if arriving later than stated (at the time of this reservation, 5€/30 min), which we were informed of in the welcome package 6 days before check-in. 30 hours before arrival, we were also informed that checking in beyond midnight (which I was anticipating at the time for our group) would result in an additional fee of 20€. After discussing with Josef, the fee was waived, but for future guests, make sure to confirm check-in times and fees with Josef well in advance to avoid any misunderstandings.
Beyond this, the apartment itself was excellent. It was very clean, and was incredibly spacious for a 4-person group. It felt very modern with 2 bedrooms, a living room, kitchen, 2 washrooms, air conditioning, a strong wifi connection, a smart TV, a washing machine for laundry, and complementary tea and Nespresso coffee available. Linens were clean and the beds were comfortable. Each room had excellent blinds (I know it seems weird for me to state this, but some other accommodations will not block out that morning sun well enough!). The apartment was located in a more modern, central area of Athens, yet only a couple of block from Mount Lycabettus, Syntagma square, and many, many nice restaurants and dessert shops nearby. You could easily walk to most of the other big touristy areas including the National garden, Panathenaic stadium, temple of Zeus, Acropolis, Plaka, and the Agora.
To get around beyond that, there are many buses that go through Syntagma square, including the Ktel bus to Sounio if visiting the Temple of Posseidon, and there is a plethora of car rental companies just blocks south of the Temple of Zeus. Furthermore, there is a direct train line from Syntagma square to the Airport, which made our departure very convenient.
Overall, even with the last-minute information regarding check-in fees, this was an excellent stay, and I would definitely consider booking with Josef again in the future. My only recommendation as I had previously stated would be to clarify the check-in process for your stay. As this is still a new Airbnb listing, I am sure Josef will continue to work on improving the whole process as well.