Willian is a great host and I would not hesitate to recommend staying with him - I would certainly happily return to his place myself.
The flat was immaculate and is located in a nice neighbourhood where you can buy food almost on the door step or go out for a nice meal around the corner.
Willian was very generous with his time in explaining things and making recommendations for things to do in the city he is passionate about. I felt very welcome and comfortable and, of course, the view of the Acropolis from the terrace is not to be missed!