I stayed in Aris's apartment with my wife and kids for four nights in mid October. The apartment is extremely well located, within a walking distance to most of Athens key sites and near tens of nice restaurants in the Psiri district. The apartment itself is as described, not luxurious but clean, tidy and functional and with a magnificent view to the Acropolis. The terrace is a lovely place to have breakfast too. Moreover, Aris had provided a nice set of books on Greece and filled the fridge with basic foodstuff for his guests to use for free!
In effect, the only drawback did not relate to Aris's apartment. During two nights, there was some kind of pop-up bar on the other side of the block that started playing music ridiculously loud at 1 AM, the bass thumping through the walls. Now if you are up and partying yourself, that is no problem. But with kids and a flight to catch the following morning, you wished you had been staying elsewhere.