Why go to an island like Serifos? I can think of several reasons: Tourists do not overcrowd the island and the inhabitants have not adapted too much to tourism. This means that you have a bigger opportunity to meet an everyday life of the Greek people.
Furthermore you will find some beautiful beaches very much worth visiting, and the island is idealistic for those who like to walk. The landscape is rather rough but beautiful.
In 1995 this was my second island to visit, but unfortunately I only was able to stay about three days, caused by ferry employees going out on strike. But my stay on Serifors was nevertheless a very pleasant stay!
Comment some 15 years later: does going out on strike solve the economical problems of Greece?