Leonidas's flat is a genuine marvel. The view from the rooftop terrace is absolutely breathtaking, the bedroom is indeed pretty small but not smaller than you may fairly expect after the description made in the offer, the neighbourhood is pleasant and the localisation is very convenient. Everything is pretty much in a walking distance and it is easy to reach from both the airport and Piraeus. In addition, Leonidas is very helpful, gives precious information and answers each time you may need his advice.
I am usually quite picky and don't like to be overexcited about everything but for sure, this flat is amazing.
I will not look for any other accommodation if I get to come to Athens again, for sure.