"I see a suit of armor around the world."

Tony Stark issues that simple proclamation to Bruce Banner near the start of 2015’s Avengers: Age of Ultron, setting in motion the machinations leading to the creation of the titular villain, a metal monstrosity voiced by James Spader. But more than that, those words clearly delineate the state of mind informing every action the Marvel Cinematic Universe’s signature star undertakes over the course of his next few appearances in what Marvel has now taken to calling “The Infinity Saga.”

Far from the superficial spectacle many wrote it off as at the time, Ultron - perhaps more than any other MCU entry - plays an essential role not merely in delving into the psyches of our heroes, but also defining their relationships with the world and each other. It has likely benefited the most from our ability to view it retrospectively and place it in further context with everything it set up.

While well received financially upon its release, Age of Ultron was nonetheless criticized by many for feeling a bit overstuffed and too reliant on the need to set up connective tissue for various other Marvel chapters down the line. (“Look, that’s gonna matter next year in Captain America: Civil War.” “Oh, don’t mind that, you’ll figure it out when you watch Black Panther in a few years.”)

And honestly, these criticisms aren’t baseless. Taken on its own, the first Avengers sequel felt less like a culmination unto itself than a pitstop on the road to bigger and better things. Without a clearer view of what precisely was being set up, one could be forgiven for wanting to write off Age of Ultron as all sizzle with no steak, the cinematic equivalent of an I.O.U.

But time has a way of adding nuance and depth to what may have appeared flat and mechanistic at first blush. And the beauty of a constantly-unfolding saga such as this means it doesn’t need to be taken on its own for very long. When viewed with full knowledge of what arrived in its wake, Age of Ultron reveals a film that stands apart in the MCU for the way it effectively embodies the many facets of the comic book universe upon which it’s modeled.

This is the only MCU chapter so far that truly showcases the Avengers as a fully-formed team, past the growing pains of their first adventure and not yet dealing with the relationship-shattering events of Civil War. While the word “placeholder” has been used to describe the film, perhaps “place-setter” is a better way to look at it. It’s a necessary bridge that allows the proper breathing room for growth and development.

From the opening “Hydra Base Attack” displaying the raw power of the team at full capacity, to the party at Avengers Tower showcasing how much of a bond these friends have forged, to their eventual victory over Ultron's hordes, Age of Ultron shows us the Avengers at full flower, with every member serving a crucial purpose and a part to play. It’s the equivalent of picking up any given issue of an Avengers comic book. Audience familiarity with this universe, far from being a debit, is the movie’s greatest strength, leaning into the then-seven years of development already in place to further our affinity for the people occupying it.

That party scene, by the way, is worthy of extended analysis all by itself. As characters weave through the many guests, we get to dip in and out of conversations that catch us up on the goings-on in the various corners of the MCU. Here’s Thor explaining the whereabouts of his ladylove Jane Foster. There are Falcon and Captain America discussing the whereabouts of the still-MIA Winter Soldier. If this were an actual comic book, it would be replete with little editorial notes letting us know which issues of Captain America or Thor we should check out for more details on what we’ve missed. It truly drives home the idea of this cinematic universe as a living, breathing thing, one that rewards longtime fans while making newbies feel like they’re being welcomed into a very special club.

All this before the central villain has even made a full-on entry into the story. And while there’s certainly a conversation to be had as to Ultron’s efficacy as a Marvel baddie (though all props in the world for how his every sinister utterance oozes with the kind of cool, cruel charm that can only come from being voiced by James Spader), the narrative steps leading to his creation and the plot events stemming from his defeat are not merely crucial in the construction of this chapter, they’re absolutely essential when mapping out the arcs of our heroes through Phase Three.

The ideological divide between Stark and Rogers, broadly hinted at in the first Avengers, is given a clear spotlight here. These men, the two alphas of the Avengers, have worldviews as wildly divergent as their life experiences. Whedon captures the complexities and dogmatic tension underlying their relationship, always just bubbling under the surface, and it’s played to perfection by both stars. That tension is papered over as the team regroups for their last stand against Ultron and ultimately defeats him thanks to the timely intervention of Paul Bettany as the sentient A.I. Vision. The two part warmly as friends as the movie wraps up (“I will miss you, Tony,” says Rogers, and doggone if he doesn’t mean it), but as we’d learn one short year later, it wouldn’t take much more to shatter both their relationship and the team itself.

Speaking of Civil War, along with its marketing-friendly “heroes vs. heroes” set-up, it also lays into place several conflicts that would play out over the next three years of Marvel opuses. And while that film’s full-scale airport battle remains a pinnacle of superhero cinema, so much of Civil War really rests on the work Age of Ultron did leading up to it. It defined “normal” for us and our heroes, offering a greater sense of what's being lost as Captain America makes his fateful decision to walk away from the Sokovia Accords, breaking the Avengers in the process.

Of course, before any of that happened, Age of Ultron famously “broke” its writer/director, who had a much less pleasant experience on this film than its predecessor. And it’s not hard to see why. While the Buffy and Angel creator has proven adept at juggling massive ensembles, the expectations placed on the follow-up to one of the most successful blockbusters ever made would tax even the most skillful franchise filmmaker. Said Whedon to Variety a year after the sequel’s release, “I was so beaten down by the process... Some of that was conflicting with Marvel, which is inevitable.”

Indeed, one can see the fissure points where the story Whedon wanted to tell - focused on one of the team’s signature comic book villains and drawn from his own longtime fandom - butted up against the studio-mandated necessity to lay ground for future entries. And yet, perhaps somewhat paradoxically, it’s precisely within those fissures that we emerge with a true sense of the film's continued value in the wider MCU canon. With four years and eleven movies of added context, it becomes clear that more than just being a key stepping stone on the road to the Infinity War/Endgame finale, Age of Ultron also occupies a unique place in the MCU firmament, one that sets it apart from what came before and what came after.