Once, Santorini must have been a beautiful little island where the locals painted their houses white and their doors, windows and the domes of their churches blue. Greece used this pretty image to advertise the country and this has attracted an enormous amount of tourists to this island. You will not find many locals here anymore but, still, it is definitely worth a visit. Especially coming off season, you can get some pretty decent deals to stay in beautiful "cave houses" and we must admit that the town of Oia is still very picturesque. Although sometimes you will need some patience to get through the "traffic jammed" pedestrian alleys and deal with the hundreds of tourists trying to find the best location to watch the sunset (and applaud when the sun has set), you can discover some more relaxing places and good areas to swim. Especially the small harbour of Ammoudi is a great place to swim and has wonderful waterside restaurants with great seafood.
So get your Euros out to enjoy this pretty island but preferably go off season to avoid some of the crowds.