Salem is one of those places that, growing up around Boston, every kid goes to on a field trip at least once. You hit the museums, and sometimes even see a silly play about the witch hunts. Thats the capacity in which Ive been to Salem.
Ive heard its fun around Halloween, never personally desired to go. Ive heard its also a mob-scene.
I think Salem is highly over-rated. All the Goths and Pagans think its so great, but its actually pretty lame.
Im giving it a “worth visiting” rating, because its worth visiting once in your life, if you live around MA or NH, but dont make a special trip there.