Nick is a perfect host! And his flat is really as good as other his guests described. But none of them mentioned the open roof in the house, in which the flat is situated. From it you can see Acropolis and Lykavittos! The view can't be compared to the view from Lykavittos, but it is pretty nice for morning coffee)
Without any doubts I recommend Nick and his room to everyone, despite the purpose of your trip: business or sightseeing.