I can highly recommend this place. The location is perfect and the flat is perfect for solo travellers and couples.
+ huge terrace
+ great location
+ very friendly hosts
+ Kitchen has (almost) everything you need
+ No technical issues
+ comfortable bed (s) and even a hammock!
+ washing machine
+ near bus stop (to Omonia)
- Wifi a little bit unreliable on some days, but no huge issues overall.
As for the people complaining about the noise... come on, this is central Athens. People party there. If you want a quiet place, chose another location but don't blame the hosts. Imho, it wasn't noisy at all. We rarely heard anything after 1 AM (teracce door obviously closed) and certainly didn't wake up because of noise.