We had a good time in Athens, and enjoyed staying in Thalia's apartment!
The location is good, about 5min away from the old Olympic stadium and other touristy things.
It's a bit at the edge of the city center, so you'll have to walk a bit (~30min) to get to things on the other side of the city, for example the Psiri neighbourhood or Monastiraki square, so take that into account when planning your day.
The inside of the apartment was very big, spacious and welcoming. The air conditioning was great (and necessary) to keep the apartment cool, since it gets a lot of sun. We slept very well, and the neighbourhoud was very calm.
The apartment wasn't exactly as in the photo: the two red chairs were replaced by a sofa and another chair, and on the veranda there was only the table and the two chairs, no yellow seats or sunshade/Umbrella. That's not a problem at all, we still enjoyed the veranda and the sun even without those things.
The only negative point would be the sofa, which was rather broken, and we would sink very deep into it when we sat on it.
All in all, it was a good quality-price ratio, and a very enjoyable stay!