I stayed at Aggeliki's flat for over a month, and really enjoyed my stay at her home. I highly recommend her flat for either a short term or long term stay.
I was working remotely from Athens, and her flat is ideal for this. The internet is very strong, and the flat has an office area that is cozy.
The location is perfect--it is just off Exarchia Square. And the apartment is much bigger than what it seems in the photos.
Aggeliki is extremely communicative, and checks in regularly to see if any more basic supplies are needed (like dish soap, etc).