Well, start with the location. The apartment is located near the train station which is good, but the surrounding environment is bad. I felt so frustrated for the first day that i arrived at Nestor's house. I was thinking of finding another place to stay since i don't feel comfortable with the neighborhood.
BUT, Nestor and his team always message us and keep in touch with us. He sent a message of what we should be aware of before our arrival. He convinced us that the place is safe (even it's a quartier noir in Athens). I read some reviews in airbnb and some that he printed and hung in his apartment, so I feel a bit release and try to adapt to it carefully.
It was fine. The neighborhood doesnt look good but they didnt do anything to harm us (we went as a group of 5). I remember we walked back from the acropolis to Nestor's house at mid-night, it was a bit scary but it's fine.
About the house, The house is very tidy and well equipped . It closes to everything , very convenience for a city-visit.
I'd recommend you to give a try on staying at Nestor's place.