This happens amid a pitched battle in which we get a traveling shot of all six Avengers each doing what he or she does best. They do so while taking on an army working for a pair of villains from prior Marvel movies in order to recover the scepter of Loki, brother of Thor (Chris Hemsworth) — an artifact from the first Avengers movie that turns out to have an unexpected connection with the Tesseract cube in that film as well as that orb from Guardians of the Galaxy and that aethery stuff from Thor: The Dark World. In this movie, that will lead to the Avengers’ most formidable challenge to date and ultimately change their team forever in an unexpected way.

With all that going on in just the opening scene, it’s a good thing Whedon can do characterization, conflict and theme in two words of dialogue. Avengers: Age of Ultron is the biggest, longest, most overstuffed Marvel movie yet; the urban destruction sprawls across multiple continents, and the cast of major characters dwarfs earlier films.

This time out, we have a) the six established Avengers; b) two additional high-flying heroes established in past Marvel movies, War Machine and Falcon (Don Cheadle and Anthony Mackie); c) two more super-powered characters essentially introduced in this film, Scarlet Witch and Quicksilver (Elizabeth Olsen and Aaron Taylor-Johnson); and d) two further characters — a villain and a hero — who are created in the course of this movie: the ruthless artificial entity Ultron (James Spader) and a role I won’t spoil here.

That’s twelve super-types — four of whom we’ve basically never met before — before we even start counting the non-super characters, like Nick Fury, etc.

The amazing thing about Avengers: Age of Ultron is that Whedon isn’t absolutely buried in all this muchness. Nearly every notable character stands out in at least one scene, and the most important characters get somewhat more than that.

Nice elements include the touching, tentative connection between Black Widow (Scarlett Johansson) and the Hulk, as well as his mild-mannered alter ego (Mark Ruffalo); a very funny scene at a party involving Thor’s magic hammer and a humanizing relationship between Hawkeye (Jeremy Renner) and a newly revealed character.

Yet you can only do so much in 141 minutes with a cast this massive, including so many new characters. Part of what made The Avengers work so well was how it pulled together an immense ensemble cast — six heroes, a villain, some SHIELD agents and a few supporting characters — nearly all of whom had already been carefully established by prior franchise films. Whedon was able to make each character connect in sketchy introductory sequences, in part because we mostly knew them all.

Here, Scarlet Witch and Quicksilver have a compelling back story, but it’s wedged in along with everything else. Scarlet Witch’s psychic powers offer Whedon a chance to get into his characters’ heads, though they also lead to some frightening images darker than anything in the first film. Quicksilver actually gets more screen time here than Bryan Singer’s non-Disney version of the character in X-Men: Days of Future Past — but nothing Whedon does with him compares with Quicksilver’s big moment in the Pentagon breakout scene in Singer’s film.

The villain, for me, is a problem. So far the Marvel universe has managed exactly one bad guy that matters, Tom Hiddleston’s Loki. This time, we get an important comic-book villain, Ultron, here presented as an artificial intelligence intended to protect mankind who goes the way of Skynet.

Archly voiced by James Spader and supplied with Whedonesque one-liners possibly reflecting the influence of his quasi-creator Tony, Ultron is more entertaining than, say, the dull villain in the last Thor movie, but with no more of a sense of individuality or inner life. Ultron is a Frankenstein figure, but one whose plight we don’t feel until his very last scene, because before that Whedon doesn’t invest him with pathos or reflectiveness. He’s just a know-it-all antagonist the Avengers have to overcome.

I’m not sure yet what to make of all Ultron’s God talk. His base of operations in an eastern European city is a ruined church that he notes appreciatively was built at the center of town, “so that everyone could be equally close to God. I like that: the geometry of belief.”

But then Ultron compares his extinction-event plans to God “throwing a curve” to mankind by sending the great flood. At another point he borrows Jesus’ words in Matthew 16: “Upon this rock I will build my church.” (Meanwhile, Thor has an unrelated remark about “the gates of hell” — or perhaps “the gates of hel,” the Norse realm of the dead and the etymological root of the English word “hell” — that doesn’t quite make sense either in connection with Matthew 16 or Norse mythology.)

Then there’s that other brand-new character created in this film, who struggles to explain who or what he is before simply declaring, “I am” — a declaration of self-awareness, but also, in light of all of Ultron’s God talk, an apparent allusion to the divine Name introduced in Exodus 3 and claimed by Jesus in John 8:53.

Later there is startling confirmation of this character’s divine worthiness. Could Whedon be suggesting that this character represents Ultron’s hope for evolutionary advancement, effectively bringing divinity into being? That would be quite a contrast to the first film, which placed a nice affirmation of monotheism on Captain America’s lips.

We also get such existential nuggets as “Humans are odd. They think order and chaos are somehow opposites” and “A thing isn’t beautiful because it lasts.” Catholics still smarting over media reportage of Pope Francis’ comment about Catholic parents not having to be “like rabbits” may wince at a line about “multiplying like a Catholic rabbit.” (On top of all that, there’s some unusually off-color innuendo.)

I appreciate that Age of Ultron is a superhero movie that emphasizes the “hero” as much as the “super.” “Ultron thinks we’re monsters, that we’re what’s wrong with the world,” says Cap. “This isn’t just about beating him. It’s about whether he’s right.” Whedon’s wit and invention are considerable, and Age of Ultron is consistently entertaining, at times exhausting where its predecessor was exhilarating.

At a certain point, the more there is going on, the less we feel it. In The Avengers, the alien Chitauri wore down the more human-scaled of their adversaries, leaving Cap and Black Widow in particular hurting and weary. The battle mattered. Here, the Avengers take on countless Ultron doppelgängers, which, as a rule, collapse after exactly one hit — an arrow, a shield, whatever.

Age of Ultron struggles under the burden of being both the grand climax to a larger saga and the setup for yet another phase of Marvel madness, including the next two slated Avengers movies (Infinity Wars Parts 1 and 2). They can’t just keep ramping it up, can they? The movies keep getting bigger, with diminishing returns. I find myself hoping against hope that Ant-Man will be really, really small.

Steven D. Greydanus is the

Register’s film critic and

creator of Decent Films.