We spent 3 weeks in the flat during which we also worked from home.
Highly recommend the flat. We stayed during winter which the heating provided was more than adequate to stay warm. The internet was good enough for two of us to work at the same time, only a couple of connection issues when we were both in meetings but overall this was not a problem so I would not hesitate to go back and with idea to work from home there.
Location is great, we really liked the area, loads of snacking bars and restaurants. Although it's in the "anarchist area", it felt very safe to us.
One of the best things about the flat though is Romanos. I've never had a more attentive host. He took the time to make us feel welcome and was always on hand to give personal recommendations in the city