There is a great deal of tragedy and some moments are even frightening and memorable. And yet, for a mainstream series, it manages to continually surprise with a very mature and serious tone. These are all common staples of long running anime series that lean towards a more commercial and public appeal.
It is very much a mainstream series, with the appeal of a huge cast of unique characters, action that commonly involves special powers, a fairly straight forward story with some mostly obvious symbolism, and a mix of comedy, action, drama, and even some romance. Fullmetal Alchemist is, in a way, unique.
