Very clean house, new furniture and high quality appliances (most advanced oven I've seen). Terrace is huge and you can use it even in rainy days
Despite being in a central place, the street is short and narrow, with almost no traffic, so it was very quiet.
There were 2 blocks until Acropolis hill and 3 blocks until a very nice commercial area with prices for locals and nice food (Kosmidis confectionery and Χριστίνα -Cristina bakery).
The area is very clean and safe, we were 7 times in Athens and every time we stayed in Koukaki.