We had a really great weekend in the little room on the rooftop. The location is perfect, everything you want to see is in walking distance. also it was easy to find, coming with the metro from the airport.
Even though the "flat" ist just one small room and a tiny bathroom, it had everything you need, even a water kettle for coffee, some kitchen supplies and a fridge.
But there are also plenty of restaurants just downstairs.
The only minus-point was that you could hear the elevator, right under the room, which might be a problem in the morning if you are really sound-sensitive.
Still, we would totally recommend staying there and would do so, if we come back to Athens!!