We were 4 nights in Athens. For some reason I didn't receive the automatic check in instructions prior the arrival, but after a short call with Alkis everything went smootly. The prior communication with Alkis was also very fast.
The apartment is exactly as described in the website and in the previous comments, clean, perfect for two persons. It has a well equipped kitchen (but no oven), bath kit is provided as well as high quality towels and bed linen. The only drawback was that the aircondition wasn't strong enough to heat the apartment (outside temperature was about 10 degrees Celsius) and we had to use also the heater in the bathroom. The windows are facing a very bussy street, so it would be pretty noisy if you keep them open during the night.
The nearest neighborhood is Ok and feel safe. The farest streets (the way to the city centre) aren't very pleasant, since there are some immigrants and homeless people that live there and make the streets messy. But if you want to skip that area, there is a convenient metro station 3 minutes away.
There is a small bakery 200 meters away, where you can buy also some groceries like milk, ham, cakes, etc. If you need some fruits or vegetables, there is a mini market 500 m away, across the main street.
It was easy to access the apartment from the airport using the blue line to Syntagma station and from there a transfer to the red line to Metaxourghio station.
Afterall, it was a pleasant stay at a convenient apartment for our needs.