A great apartment in a really good location. You can walk to most places you would visit as a tourist in Athens. The metro stop and bus routes are really close. Some good local restaurants, cafes and bars.
One thing to check is the strikes. There was a strike on the metro when we arrived but we just got the bus from the airport so a little longer walk but no hardship.
Konstantinos is a great host and will help, just ask him.
A great time had in Athens.