Lovely little place, windows to the yard ( I imagine nice for breakfasts outside- I stayed in January ...), newly renovated, very clean and comfortable all in all. Easy airport connection (Ambelokipi station), 15 min walk down Ippokatous street to Exarchia district (restaurants and bars galore), 15 min walk to the Mount Lycabettus (great view over Athens and a lovely walk). Bus 230 to the Acropolis , half an hour walk to Psirri (or bus connections too . Walk is nice though- you get to cross all major arterial streets).
Helen and her husband are very nice, warm people (the sort you had known for 5 min and already want to include them on your kids christenings and weddings invitations lists), extremely helpful and welcoming. Pics and the description on airbnb web side are very accurate.