Pyrgos is a very nice town, pretty centric and well communicated. We even skipped renting a car and got everywhere by bus (normally via Fira). Also this apartment is located very close to the castle, in a very calm place, but surrounded by shops, restaurants, the bus stop, ...
Nefeli was an awesome host. She was always available, her communications skills are superb, and she knows the islands very well so she provides the best recommendations.
All in all, great place to stay!