Appartment is new, clean, centrally located (really, you can't be any more centrally located in Athens). It is perfect for a couple, I reckon it could also be good for 4 persons.
If location and cleanliness is paramount to you, look no further.

Mike was an excellent host. Communication was always prompt. He offered to show me around the center the first day and provided everything needed for a breakfast in the fridge. There is also a capsule nescafe machine on the kitchen counter, for some excellent morning or afternoon coffee.

Overall verdict of the flat and the host: excellent