We absolutely loved Argyro's place. She was absolutely lovely to communicate with, and Mimis was exceptionally helpful and kind while showing us around when we first got there. The space itself is perfect, and there were a lot of thoughtful touches included to make it even better. The balcony view is perfect for watching the sunset. As a whole we felt very safe here! The building has great security measures and the surrounding area has a good amount of police.
A bit on the neighborhood: I've seen some concerns about the neighborhood as it is located in Omonia. However, as long as you stick to walking on main roads it really does not feel unsafe. Avoid taking Menandrou south straight when you go to the Acropolis as that was probably the only "sketchy" area we encountered.