Since the olden days of 2008, Marvel Studios has been laying the big, heavy groundwork for what comes blasting into American movie houses today (it's already been tearing up foreign markets for a week). Beginning with the smash hit Iron Man and diligently continuing on with The Incredible Hulk, Iron Man 2, Thor, and Captain America, Marvel has been building a world of back story and character, all setting the scene for The Avengers, a superhero mash-up movie of, if not epic, certainly cosmic proportions. The end product of four years' worth of sneaky post-credits scenes and other teasers, this enormous summertime kick-off film comes weighted with not just its innate scope — four leading men superheroes jockeying for screen time! — but by a boatload of rabid expectations. This is either the superhero movie to end all superhero movies or the one that begins something new, evolves an already lucrative franchise into something even bigger — it's a popcorn flick with the potential to transcend into a higher plane of box office existence. And thus Marvel and Disney and everyone else who paid for this thing, and we audiences too, are awfully lucky that writer/director Joss Whedon, already having a good spring, has made something so giddy, so buoyant, so rattlingly fun. It's a superhuman feat!

This is not to say that the movie should win Oscars or anything. It is still, of course, one of Marvel's mostly nonsensical explosions of noise and light. While it's not entirely important to have seen all of the Avengers lead-ups, the better informed viewer will at least be able to make some sense out of the film's cluttered plot-establishing scenes, which involve some sort of magic glowing cube, first seen in Captain America, the dashingly evil villain Loki (the mesmerizing Tom Hiddleston), from Thor of course, and Samuel L. Jackson wearing an eye patch — here he's Avengers leader Nick Fury, a guy we've glimpsed in most (all?) of the previous films' post-credit sequences. So yes, it is somewhat helpful to know the vague details of the setup, but it's by no means necessary. Because what the film is actually about is of very little consequence. All we need to know is that a bad guy is about to do a terrible thing and that lots of innocent people will be killed if he does it. But, for the particulars-minded among us, this cube opens a portal between worlds through which Loki hopes to transport an army of alien conquerors, in exchange for, I dunno, vast intergalactic power or something. The situation is both grim and mostly incomprehensible to the mere mortals on Earth, but they at least know one thing: They need to get this band of super freaks together so they can save the day.

The first of the film's many neat tricks is that all of our heroes are pretty reticent to join this can-do collective. Tony Stark (Iron Man) has his bristling ego, Thor just wants to collect his brother Loki and deal with him back on their planet, and Mark Ruffalo's Bruce Banner (The Hulk) wants to hide away in peace and quiet lest he go green again and make some more oopsies. Only Steve Rogers, our lantern-jawed post-cryo-sleep relic Captain America, is willing to buckle down and follow orders. So, after being assembled by Fury and his sexy, slinky hired assassin Black Widow (a game Scarlett Johansson), and brought to a fantastically insane enormous flying aircraft carrier, the brawny dudes bicker and, at times, come to blows. We know they will eventually band together to save the world (America first, of course) but we have a good time watching them squabble on their way to the inevitable group hug. Whedon's script gives Robert Downey Jr. (as Tony Stark/Iron Man) plenty of his trademark zippy, reference-y one-liners ("Stark snark"?), while the innate ludicrousness of Chris Hemsworth's Thor — a big beautiful blond Scandinavian warrior sex-alien who speaks as if from medieval times — is teased at throughout. The entire movie is rife with Whedon's dextrous humor, full of moments of levity popping up with precision timing amid all the comic book-y end-of-the-world seriousness. Marvel made an inspired choice when they entrusted Whedon with this ridiculous assignment, and he proves his merit again and again over 142 rollicking minutes.

Perhaps the most important thing that Whedon does well is give everyone what feels like near-about equal screen time. No one hero stands out as more of a lead than anyone else, and everyone has some little bits of business all their own, each possessed of at least some half-formed motivation. Even the secondary, non-power-blessed normals like Black Widow and Jeremy Renner's Hawkeye play integral parts. It's an egalitarian movie that becomes collectivist by picture's end, with every Hulk smash and Thor hammer blow (which occur thousands of feet up in the air, in a darkened forest, in the streets of Manhattan) working as part of a larger Voltron-esque avenging machine. Marvel, through its careful and smart hiring of various writers and directors, has done a remarkable job of making each film in the lead-up to Avengers its own standalone entertainment and yet also a tonally and aesthetically similar part of a larger whole. In The Avengers we see the satisfying sum of that deceptively careful work and it is an at-times eye-popping wonder to behold. There are a few narrative clunks and groans along the way to be sure, this is to be expected when you've so many moving parts to contend with, but on the whole The Avengers is a terrific, shiny, surprising success.

While some aspect of this endeavor should feel cynical — this is merely a guaranteed smash cobbled together out of other movies — Whedon and his able company seem to be having so much fun, seem to so genuinely care about making a Freakin' Awesome Cool superhero extravaganza, that any of Marvel's bottom line greed ceases to matter. Yes they will make a bazillion dollars on this, and there will be a sequel, and the whole thing will start to feel old eventually, but for now it's just righteous month of May entertainment. We may be too old to play with action figures, but at least here are The Avengers, bringing those madcap kid fantasies to vibrant, colorful life.