This apartment is the perfect location in Athens. It's right next to Plaka which is a gorgeous district with loads of restaurants and shops. It's easy to get from the apartment to all of the attractions, the furthest one is only a 30 minute walk away, most are much closer. The flat was spotless and had everything we needed, check in was super easy and Efi was easy to communicate with.
The only downsides are that it's very noisy. The walls are thin so you can hear everything in the apartments above, next door and on the balconies nearby,. On our last night we were woken at 3am by a very loud party, even through earplugs I could still hear them yelling. For most people it would be fine, but definitely take some earplugs if you are a light sleeper. Another that lets it down slightly is that it's quite dark in the apartment. If you're planning to be out and about all day that won't be a problem though! The TV is quite old and so you can't really watch Netflix on it, again, most people won't mind this but when we wanted to relax and watch some TV after a super busy day, it was a little frustrating.
Overall I definitely recommend the apartment, I honestly don't think there is a better location in Athens!