Man of Steel. Henry Cavill, Amy Adams, Michael Shannon. Directed by Zack Snyder. Rated PG-13. Opens Friday.

First of all, it’s another damn origin story. Superman’s origin is not only the most well-known piece of superhero lore, it’s also an established piece of American mythology, and as such does not need to be rehashed every time the character has a new onscreen adventure. Or, at least, it doesn’t need to be rehashed at this length, in which it takes 20 minutes just for baby Kal-El to be sent forth into space from his dying home planet of Krypton. But since Man of Steel is a modern superhero blockbuster, this is all standard operating procedure: The movie runs nearly two and a half hours and has to turn every little bit of storytelling into an operatic, explosive set piece.

Director Zack Snyder actually seems most at home in this early sequence, however, getting to indulge his penchant for stylized, ornate action. Snyder’s Krypton is full of ridiculous impractical costumes, strange winged beasts and insect-like spaceships battling under an ominous sky. The movie’s first 20 minutes are as cloying and overstuffed as Snyder’s most exhausting past work (bludgeoning epics like 300 and Sucker Punch). It might be painful to watch, but it at least has a recognizable style.

Then the movie crashes down to Earth, and it turns into a long slog through familiar elements of current action-blockbuster filmmaking. Producer Christopher Nolan and go-to superhero screenwriter David S. Goyer craft a story that recalls Nolan’s three Batman films, completely grim and humorless and plodding. That often works for Batman, but Superman is meant to be an upbeat embodiment of the American spirit, an outsider who comes to Earth and embraces everything good about humanity. The version in Man of Steel (played competently but unexceptionally by British actor Henry Cavill) is tortured and often angry, and although he does become a champion of humanity, he does so in an almost threatening way.

That’s partially because he has to participate in a giant action climax that uncomfortably recalls the final battle in Michael Bay’s third Transformers movie. Villain Zod (Michael Shannon) is a fellow Kryptonian refugee, but his plan is fairly generic world-ending stuff, and its execution involves the wholesale destruction of downtown Metropolis. Buildings collapse as Superman and Zod whale on each other, and the supposed greatest do-gooder of them all only has time to save Lois Lane (Amy Adams).

Snyder, Goyer and Nolan are all pros at this kind of large-scale filmmaking, and Man of Steel certainly has its moments of excitement. The always creepy Shannon makes for a solid villain, and some of the flashbacks to Superman’s Kansas upbringing are nicely handled. But overall this is just another product of the proven superhero-industrial complex; it’s part Thor and part Dark Knight and part Transformers, when it should be all Superman.