We visited this penthouse twice in September 2011. It's a very nice setup of a small roof apartment surrounded by a very nice "roof garden". It is located in the "young and lively" district of Exarchia Square. Don't expect for a fancy apartment, but it is clean and has all the required amenities including air-condition where middle class guests will feel at home.
Yagos, the penthouse owner is a quality and reliable person and who go out of his way to help his guests.