Great apartament, clean, spacious, 15 - 20 minutes by walk to Monastiraki, Syntagma and other touristic points.
Close to Omonia square which is considered not the safest place in Athens during the night (you may see some drug addicts and prostitutes). However, it was my second time booking in this area and never had any problem. During the day, Omonia is safe, lively and has some very nice places to eat and drink coffee.