It's nice, well designed and well-equipped place for people who are arriving to Athens to sightsee. You can drink coffee and eat some breakfast on the courtyard. This apartment has everything you need on the little space, but for us it was enough. It's really comfortable and the location is amazing, next to the Acropolis. You can see almost everything without using the public transport.
I can truly recommend this place. Thank you for your hospitality! We had an amazing time in Grey Matter.