When we arrived at the apartment Dimitiris' father welcomed as (although our flight was a few hours delayed, they tracked the times and adjusted) and showed us everything in the apartment, not before offering a local Raki drink.
They where very flexible in check-in and check-out hours and allowed a very early check-in and very late check-out, according to our flights' hours.
The apartment is spacious (i think it's bigger then it looks in the pictures) and well equipped (shampoo and soap, many towels, coffee, water bottles, beers and juice, in addition to kitchen utensil).
A downside was the air conditioning - it is in fact a portable air conditioner, which wasn't strong enough to make the place cool in July weather. There was also a fan for ventilation.
Location is great - a few minutes walk for a metro station, and another few minutes walk to the Monastiraki Square and flea market, where there is a main metro station, restaurants and taverns to eat and drink, bars etc.
Overall we had a very nice stay, but must mention it is not for people that like cool temperature and tend to stay in the apartment.