After Earth's Mightiest Heroes went their separate ways at the end of 2012's Marvel's The Avengers, producer Kevin Feige said in several interviews that, for this team to come together again, it has to be for something truly monumental, because each of these heroes could surely handle lesser threats on their own. Of course, an evil alien race attacking New York City in the first movie is certainly a viable reason for this team to come together, but what's so intriguing about the Avengers coming together once again in Age of Ultron, boils down to the fact that one of the Avengers literally creates the villain they must go up against. While the sheer magnitude of the story does get away from itself at times, Avengers: Age of Ultron is still a triumph, giving some of Earth's Mightiest Heroes more to do, while introducing a few key new members in glorious ways... although it's not quite as good as Marvel's The Avengers.

The movie opens in quite a thrilling fashion, with an enormous action set piece that eats up anywhere between 20 and 30 minutes of the movie. I wasn't expecting the sequel to go so big, right off the bat, but the story starts with the Avengers on their way to pay the villainous Baron Von Strucker (Thomas Kretschmann) a visit in his massive European compound, which is where we first saw him in the end credits scene in Captain America: The Winter Soldier, along with siblings Pietro Maximoff, a.k.a. Quicksilver (Aaron Taylor-Johnson) and Wanda Maximoff, a.k.a. Scarlet Witch (Elizabeth Olsen). This scene shows how much of a well-oiled machine the Avengers have become (including that simply amazing shot of them all literally springing into action), but also eventually plants the seeds for Ultron's creation as well, after Tony Stark (Robert Downey Jr.) finds some important tech that could be useful to him in Strucker's compound. See, Stark wants to put "an iron suit around the world," protecting it from those aliens who attacked New York several years ago, and any humans who wish to do the world harm as well. As noble as his intentions may be, Tony and Bruce Banner (Mark Ruffalo) somehow give birth to Ultron... even though neither of them are quite sure how it happened.

RELATED: Avengers Campus Is Officially Open at Disney's California Adventure Theme Park

There is a lot to love in this sequel, especially if you are one of those (like me) who felt that Jeremy Renner's Hawkeye and Mark Ruffalo's Hulk weren't used to their full potential in the first movie. There is an entire sub-plot revolving around Hawkeye that has somehow been kept a secret this whole time (especially since other key details have already leaked) that I won't spoil here, but I will say that you'll certainly look at Hawkeye in a whole new light. As for the Hulk, it's no secret that he'll face Tony Stark's Hulkbuster armor, but the details behind why the armor was created makes a whole lot of sense when you see the whole movie, and his unique relationship with Scarlett Johansson's Black Widow is quite wonderful as well. As one would expect, with Joss Whedon writing the script, there are some fantastic bits of comic relief, including a wonderful running gag about Captain America's (Chris Evans) aversion to adult language, plenty of new Tony Stark one-liners and a humorous bit that was already seen in previously-released clips that shows the entire team trying to wield Thor's hammer Mjolnir. Somewhat surprisingly though, Jeremy Renner delivers possibly the funniest line of the entire movie, a self-deprecating bit where he makes fun of his choice of weaponry.

As jaw-dropping and enormous as this sequel is, that might actually be to its detriment, as there are a few scenes and plot points that feel muddled and somewhat out of place. You may recall hearing a few weeks ago that the "mystery woman" who was seen disrobing in the first trailer is not featured in the movie, and she isn't. While this normally wouldn't be a huge deal, it does hint that there is a much larger sequence involving Thor (Chris Hemsworth) in this cave. While it does prove to be a pivotal moment in the story, due to what he discovers, there just seems to be so much more there that was likely cut for time. Still, these oversights aren't terribly glaring, but there were a few times where certain scenes just struck me as odd. Although, since this is such a huge undertaking, with countless proverbial plates that need to be kept spinning, the movie as a whole is still incredibly impressive, nonetheless.

I'd be remiss if I didn't at least mention the newcomers we see in Age of Ultron. Elizabeth Olsen is just fantastic as Scarlet Witch, whose mystical abilities wreak havoc for Earth's Mightiest Heroes when they first meet. Aaron Taylor-Johnson is just as good a Quicksilver, but he's almost seen as somewhat of a novelty, compared to his sister's incredible powers. Then, of course, there is Paul Bettany's Vision, who I don't want to talk too much about, other than to say he is certainly a welcomed addition. James Spader is rather brilliant as Ultron, whose petulance and overbearing personality most certainly comes from one of Earth's Mightiest Heroes, but the befuddling nature of his creation (let's just say the Science Bros don't exactly know how it happened) is another head-scratching moment that, in the grand scheme of things, isn't terribly detrimental to the quality of the movie as a whole, but still puzzling nonetheless. As I mentioned before, with Hawkeye and Hulk getting more screen time, and with all of these new additions, there are plenty of times where it seems the rest of the Avengers are taking a back seat, which makes sense since the rest have had chances to shine in their own separate adventures, but, if anything, it shows how truly massive this sequel is, not just from a visual standpoint, but from a story perspective as well.

It's surely no coincidence that the next time we see the Avengers will be in a two-part movie, which has become a popular technique for studios that want to stretch out their young adult franchises for as long as possible, taking the last book in a series and making it into two movies. While that practice seems ill-advised for projects like those, it seems like just what the doctor ordered for the Avengers, which is getting so big that it simply needs two movies to contain it all. If the sequel proves anything, it's that Earth's Mightiest Heroes are just too big for one movie, and while the result will surely leave fans satisfied, it still falls just a bit short of the original Avengers movie... but not by too much.

Age of Ultron hits theaters on May 1, and stay tuned for our interview with producer Kevin Feige as we get closer to the release. If you agree or disagree with my review, let your voice be heard below, or on Twitter @GallagherMW. Does this review make you more excited or less excited to see Earth's Mightiest Heroes on the big screen again?

The views and opinions expressed in this article are those of the author and do not necessarily reflect the official policy or position of Movieweb.