If you're a fan of the series, you need no introduction, you need to go see this immediately. If you're new to the whole Harry Potter phenomena, this is NOT the place to start: instead go see the other films in order, as there is not one bit of development on the characters--it is assumed you know who they are and already have a vested interest in them...which makes sense becuase, after all, this is the 7th movie in the series.
Harry and friends are pitted in their ultimate battle against time in this race to destroy all the items that keep Voldemort alive, This is the beginning, it is culminated in the next movie, where much will be explained, so as I said, don't expect much explanation in this installment.
Is it good? Yes. Should you see it? Yes. Is it as magical as the earlier installments? Not really...yet.