We only stayed for one night, but loved the apartment. It is great for 2 people with a comfortable bed, great living room and balcony, and nice kitchen we that is great for making a quick meal!
Costas was a great host as well and met us and gave a tour of the apartment, and was always quick to respond to any messages.
The apartment is a quick walk from either of two metro stops on the red line. Maybe 10 minutes with luggage. If you have roller bags the sidewalks might make it a bit slower, but we had no problem.
A lot of big sights are within walking distance if you up for a longer walk, or you can take metro easily too.
It was great for our quick second stop in Athens.