The apartment is amazing. Espezially for big groups. We never had the feeling there would be too less space. We were 16 people. 3 of us slept in the apartment on the 3rd floor, which was also great. Dora offered this solution for us beforehand in order to have enough beds. But the main interactions happend on the rooftop. Here we made breakfast and spent the evening chatting and playing games.
Also the location of the apartment is great. The most important sights are in walking distance and you can get a feeling of Athens way of living and street culture. Also 2 mertro stations are very near. I would recommend all big groups to stay here!