We were on Paros just before the season and just before the crowds and many hotels and restaurants were still closed, but it was still a very pleasant experience. In large part, this was due to where we stayed: Anezina Resort at Dryos, an RCI resort. It was small, well located, quiet, well appointed, and so typically Greek. The buildings were two stories tall and painted blue and white, set in gardens full of flowers, olive trees, and cats.
The staff, including the owner, Maria, was always friendly and helpful. We had to stay another night because our scheduled flight out was cancelled and nothing was too much trouble for Maria. The food at the Anezina cafe-restaurant was good, typically Greek, inexpensive, and accompanied by cheap, drinkable wine and souma (the local version of raki).
Paros island itself was covered in wild flowers and their perfume was pervasive. It is easy to get around with a car and the local villages are relatively easy to navigate if you take it easy, unlike some of the locals. The beaches were great for long walks, though it was too cold to swim. The main towns have all the services one could want or need and lots of restaurants and interesting shops.
My recommendation would be to go in late September/October while it is still warm, but the crowds have thinned out.