My father got a weekend in Athens for his big birthday. From the moment my parents arrived to the very last day they loved every single minute of their stay in Athens. Warm weather, Greek food and sights/history and lots of walking - they loved it! No obvious signs of the financial crisis btw.
As the apartment is only 10-15 from all the sights you won't really need to use public transport to get around Athens. It is immaculately clean, quiet, well maintained, equipped with anything you could possibly need. A welcome bottle of wine was a very pleasant surprise. Communication with Maria and Danillo was fast, accurate and seamless.
There is a great bakery opposite the flat and it offers freshly baked treats. On the day of my parents' departure my Mum was given a special pastry gift from the owner!
My parents recommend Maria's apartment wholeheartedly. So now it is our turn to visit!