Stayed at Konstantinos place for 5 nights recently. Instructions for check in were very clear and made the process quite simple and fast. The apartment was clean and well furnished, with all the common amenities. It's located on a fairly busy street\intersection, but the noise from outside was never really noticeable. The location is fantastic, with nearly all the major sights in Athens within walking distance. I'd not hesitate to stay here again when I return to Athens!