Mary & Theo's place is very nice and well-located, in an interesting and vibrant (and safe) part of Athens - less than 10 minutes' walk to Exarchia Square, but without the noise.
Mary was there to meet me when I arrived, and she was always readily available on Whatsapp. The bedroom is very comfortable and sunny, with lots of wardrobe space and a pleasant small balcony. I never had a single issue with the WiFi in 1 month. Supermarket just downstairs, super handy.
The only downside was that the kitchen gets no natural light at all, and there's not a lot of hot water after the boiler's ready, so you have to settle for relatively quick showers (but that's the norm in older apartment blocks in Athens, I guess).