The apartment is fantastic in terms of amenities, and the shower is the best thing. There is plenty of space for 4-5 people to share which was great for us. In terms of value for money then you get plenty. As for the location ...it is in a part of Athens which has seen better days but other than that the neighbourhood is safe and the locals are fine. It would take us about 15/20 minutes to walk to omonia and there is a local train/ metro station 5-10 minutes away.
I would definitely stay there again if I went with friends.