We were staying in Ischia Porto and could see the Castello from our bedroom window so a visit was a "must".
The walk to Ischia Ponte is really pleasant combining shops and beaches and we found a delightful small restaurant facing the sea near the castle for a well earned lunch !
The castle is fascinating combining many centuries of history but the artwork on display leaves much to be desired ! The panorama from the various levels of the castle, particularly the top cafe, are simply stunning taking in the Bay of Naples and its environs, a camera just cannot do it justice.
If you are visiting Ischia, the Castello is an essential part of the experience.More