I moved my family to Marblehead from the Midwest 5 years ago. Generally speaking, we've been very happy with the move. Here's the good and the bad:
This is a really nice place to raise kids -- it is really safe, with a protective community with lots of things for families to do.
We've been generally quite happy with the schools. There has been a big move to renovate the schools, and the vast majority of teachers we've had have been excellent. Schools in Massachusetts are generally underfunded relative to other states (having lived in 3 other states -- these are the worst -- not much left after the state taxes and bureaucracy), but Marblehead's have gotten consistent override support and there are active parent organizations which support the schools.
There is a healthy mix of old-timers and new people to town. We've generally found it welcoming.
Traffic is an issue. I work only 3 miles away in Salem -- it takes 20 minutes to get there. Unless you live on Marblehead Neck, there is no school bus system -- the traffic mess at school time is ridiculous.
As noted in earlier posts, you are a distance from everything: it's 40 minutes from I-95, and at least 45 minutes from Boston.
Restaurants- the yacht clubs, with their requirement that members spend a certain amount dining, suck the life out of the restaurant scene. They are generally bad and overpriced. If we go to a movie (no theater in town by the way) and want to get a bite to eat after 10, we have to go to Salem.
Hope this helps. If you move here, I hope you have a terrific experience.