Konstadinos's place is really what it looks like: well equipped, comfortable, quite big apartment, where your stay in Athens will be really well provided. We've spent a little bit more than one week in Athens, so it was a priority to find a place "like home", where you don't have problems to live an everyday life - to cook, wash things, have showers, rest a bit in the airconditioned room if it get's that hot as it got during July... And so on. The communication between us went very well, Konstadinos answered every question, even recommended not that touristy places, so don't hesitate to ask him about such recommendations!
Only one thing that you should consider, but it has nothing to do with the host's efforts: the apartment is located in Metaxurghio, which on one hand has a really great connection to the city center and the outskirts, even by foot it's just a 10 minute walk to get to Monastiraki square. But on the other hand, unfortunately it's not the nicest district: although the house itself is really safe, but on the streets nearby you cannot avoid junkies and strange-looking people. Fortunately, we didn't have any bad experiences with them, but it's best to consider if you want to wonder on the streets alone.