We had a 2 nights stay at Kostas and Vasso's apartment and enjoyed it very much. The building and the flat are modern and nice. Our ensuite bedroom was immaculate (bedsheets and towels smelled good!) and very comfy.
Kostas is very easy to communicate with and flexible. He and Vasso are very welcoming people.
We highly recommend staying with them to anyone who has to do in the neighborhood (we wanted to be close to friends who live there), also as a base to visit the city if you don't want to splurge for a central location. Although it is not the most central nor fancy area, it has easy access to the city: 2 stops only to Kings Cross/St Pancrass, 7 stops to Covent Garden.