We had a good time at Sia's place.
The location is very good, just a 10 minutes walk from Sigrou-Fix metro station, with several options concerning restaurants, supermarkets, pharmacies, etc., very close to it. We didn't feel any safety issues as other guest mentioned or even noise.
For us, the bed was comfortable and we slept very well. During the first days of our stay, the weather was cold in Athens, but we felt no cold in the appartment and we didn't even turn on the AC; the heating system was enough.