We spent two nights at Nasos' apartment and loved it. Nasos picked us up from Syntagma station, and walked us to the apartment, which is smack in the heart of it all. Only a few minutes walk from the Akropolis, the Akropolis museum, Roman and ancient agora, the Arch of Hadrian and so on.
The apartment itself was perfect for two people, and the AC was very welcome given the hot temperatures in Athens. Nasos had water, cookies and a couple of snacks waiting for us, which was brilliant for two very jet-lagged people.
While you're there, make sure you try out Thanasis' Kebabs, and A for Athens for an amazing night rooftop view of the Akropolis.
Nasos was a fantastic host and we would definitely stay here again.