This apartment is a great place to stay for a visit to Athens. It is so convenient for the Acropolis and the main historical sites and it is also in a very nice neighbourhood - the restaurants in the opposite direction to the Acropolis were all great and fantastic value.
The apartment was clean and everything worked fine, including the shower. Only comment would be that the kitchen is pretty small and there is not much space to eat in (the only dining table is on the terrace) however, assuming you are not coming to cook and eat in, then you'll be fine.
We did not meet Eleni, but the self-check-in process worked really effectively and meant that there was no anxiety about us arriving later in the evening.