The apartment is amazing: veru specious, light and modern. It was super duper clean when we arrived. The location is very convinient if you want to do sight-seeing, relax in bars and have nice meals or do loads of shopping..it is all walking distance from the apartment :)
Stamatis is the best host. Very responsive and helpful. He made sure we know how to get to the place and was always there if we needed anything. Also left a helpful map and suggestions of places to visit in Athens. :)
I would very much suggest to stay in this aprtment if you are visiting Athens.