We stayed here twice; the first being on our way in through Athens to the islands, the second time being our trip out.
This is a great place for a couple or solo traveler! The flat is in one of the nicest neighborhoods of central Athens with a quiet setting. The flat itself is recently renovated and beautiful with all the amenities you could need even for a longer-term stay. The self check-in experience was clear and easy.
The only thing I would bear in mind is that the location is at the top of Kolonaki so it does require a bit of a climb up stairs or a street.