The latest installment in the Marvel universe film world is such a box office phenomenon (already at more than $1 billion internationally) that it seems inconsequential or trifling to attempt a real analysis of the thing. Yet on we trudge….

For what it is, AAU manages, sometimes barely, to hold all its disparate parts together. It’s not the surprise the first Avengers film was, and its reach does exceed its grasp. But for the most part, it succeeds in holding together a huge cast of primary characters, a few secondary ones, a cosmic earth-threatening menace, something of a possible love story, and a hefty supply of amusing one-liners and quips.

The first Avengers film was a revelation in that it gave place (if not equal space) to a variety of Marvel characters that seemed as if they would never find a common cinematic place to meet, much less live in and share space and time with one another. But writer/director Joss Whedon does it again, this time with even more characters. While the addition of more characters sometimes makes for a slightly bumpy and disjointed film, Whedon nevertheless succeeds in re-creating a believable world for these wildly different superheroes.

The film is darker in tone than its predecessor, à la The Empire Strikes Back. The film assumes that you are aware of the various characters, their powers, their personalities and how and with whom they clash. The story, though, is essentially a repeat: Earth is threatened, Avengers must get over their personal issues and differences, and they must unite (“Together!”) to see victory. As in the first film, the climactic moment is not a final battle, but the creation (or here, re-creation) of a cohesive team. There is even a near-total repeat of the 360-degree camera movement unifying the distinct individuals.

What makes this equal to the first (no worse, but no better) are the variations from the first; some succeed, some don’t. Poor Hawkeye (Jeremy Renner) was given short shrift the first time out. This time (spoiler alert), he’s not only given more screen time; he’s given a family and a big country “safe house” with adoring wife and children. It’s certainly more backstory than any of the other heroes get, and if Renner was unhappy with the first outing and his little time in that film, he has been more than repaid in this one.

We also have two new heroes introduced, twins first created in a Mengeles-like experiment for evil purposes, but who (spoiler alert again) eventually join the Avengers toward the end. They are played effectively by indie favorites Aaron Taylor-Johnson and Elizabeth (sister of the twins) Olsen. I was wondering during the film why I was getting to know Scarlet Witch (Olsen) so much better than her cinematic brother Quicksilver (AT-J), but (spoiler alert!) I found out why by the end of the film.

There is also (another spoiler alert, but you really don’t care) a just barely believable romance that is budding between Natasha (Scarlett Johansson) and Bruce Banner/The Hulk (Mark Ruffalo). It’s not clear to this viewer how that came about, though both are first-rate actors and bring some real longing and angst into a world generally devoid of such emotion. Its best moment, however, is when it’s played for a laugh, which tends to be highly enjoyable while it undercuts the depth of feeling of the two.

Perhaps the weakest part of the film (not the weakest moment—we’ll get to that) is an apparent attempt to address the issue of human collateral damage. There was some criticism of the first film regarding all the damage caused by the various battles and the huge toll in human life taken by the heroes—particularly the Hulk—while they are trying to save humanity. So here we pause to save a few people—a woman in a car that’s just about to fall off a broken bridge, a young boy who needs rescuing from the detached city (don’t ask). But we don’t know these folks in particular; they are given little to no backstory, and it all comes off as a lame attempt to show that these mighty warriors care about the little people and the individual. Meanwhile, the Hulk goes on his rampages, not all of which have positive aims. We see fewer casualties, but one can guess that we have as much human damage as in the first film—we just don’t see as much.

The worst moment, however, is one that may well be the one that I’ve been talking to my film class about for a few years now. When we get to the subjects of metaphors, allegory and allusion in class, I often talk about the most powerful visual in recent American history—the events of 9/11—and wonder when and how the first major filmmaker will allude visually to that event. Here, there is a tall building that pancakes down to the earth. We’re told it’s empty (so no human casualties) and there are no other specific resonances that reach back to that tragic day. But to anyone who was old enough to see the collapsing towers, it’s disturbing and confusing to say the least. If it’s a reference to 9/11, it’s a failure, on every level.

The plot replaces the evil Loki with Ultron, a creation-gone-wrong from Tony Stark/Iron Man (Robert Downey, Jr.). To make this happen, we have to see Tony go back in a dark/stubborn/egotistical state, one that is logical but unpleasant to see. Yes, it creates more internal conflict within the group, but it’s nowhere as engaging and definitely not as amusing as some of the conflicts of the first. We’ve also lost the inestimable Tom Hiddleston, one of the greatest villains in film history and one of the most watchable actors working today. His absence is palpable.

Fortunately, the voice of the CG Ultron is by the dark-and-silky-voiced James Spader, who has a different kind of intelligent snark as Loki. Spader’s style is less engaging and more detached than Hiddleston’s, and Ultron doesn’t quite find his way into the Marvel universe with the same ease as Loki. Ultron is supposed to represent the horrid and dangerous endpoint of the current thinking that since we humans are to blame for every social and environmental ill, the smartest thing to do to save the earth is to remove all the humans. It’s a fascinating thought to play with (and perhaps comment on), and the film could also have explored the idea as a distortion of one of Tony Stark’s bent thought patterns. But the film does nothing with either possibility, and we are simply left with a bad guy bent on destruction. Then the bad guy creates clones, which are more annoying than threatening, for both the movie heroes and the viewers. Too many holes in logic are created by the whole thing (e.g., why couldn’t the Hulk just take out Ultron?), but logic isn’t always in the forefront when it comes to setting up battles.

And as in the first film, those battles just go on too long. Not to Man of Steel lengths, thank God, but too long nonetheless. Yet there are moments of beauty that reminded me of what genius cinematographer Jack Cardiff did in 1948’s The Red Shoes. In that film about ballet, he ingeniously slowed down the film at a few points when the dancer was at the peak of his leap. It’s almost unnoticeable unless you’re looking for it, and its effect is breathtaking. AAU does the same thing in the midst of the battles, and the effect lends depth and beauty to sequences normally full of noise and special effects.

Lastly, the film works hard at staying earthbound, and nowhere is that more apparent than in the constant stream of quick one-liners and comic remarks among the various superheroes. Most come out of character, most are genuinely funny, and they all prevent the film from flying out of earth’s gravitational pull. This is clearly Whedon’s goal throughout, and perhaps the film’s greatest triumph is keeping the characters, plot lines, and pieces of the Marvel universe in some kind of orbit. The occasional scene comes out of nowhere (except perhaps the Marvel books) and they aren’t well integrated in the film as a whole [e.g., Thor (Chris Hemsworth) flailing about shirtless in some confusing substance]. But for the most part, Whedon has managed to hold together an unwieldy collection of conflicts and characters into something of a relatively cohesive whole. For a behemoth, American, moneymaking, nerd-world machine, that’s quite the feat. Will there be a hat-trick?