Pacific Rim is, as you might expect, a visual extravaganza brimming with lush colors, state-of-the-art CGI effects and the promised robots on monsters hard-core fights to the death. If the world were a cage, this would be the underground, "the rules are there are no rules," cage fight to end all cage fights.

The basic premise is that giant monsters, called Kaiju, have invaded earth and are threatening an extinction level event. The military has built 26-story tall robots, called Jaegers (hunters), to battle them. It's humanity's last days, and the survival of the world rests in the hands of an embittered ex-Jaeger pilot, Raleigh Becket (Charlie Hunnam), his untried co-pilot, Mako Mori (Rinko Kikuchi), a wacky scientist, Dr. Newton Geizler (Charlie Day), a black market "monster parts" dealer, Hannibal Chau (Ron Perlman), and the pilots' fearless leader Stacker Pentecost (Idris Elba).

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As the "go big or go extinct" tagline would indicate, the movie swings big, and when those hits land they are spectacular and truly breathtaking. When they don't, however, as is the case with the bulk of the human elements in the film, the effect is dissatisfying at best and cringe-worthy on occasion.Throughout the course of the production, the joke was that Warner Brothers had given director Guillermo del Toro $200 million to make the movie that his inner twelve-year-old boy had always wanted. Indeed, that is what ends up on screen. This is the two-hour, live-action mecha anime/Toho monster movie mash-up that a young and enthusiastic del Toro must have fantasized about.There is something wonderful about that, and in moments the film really does tap into our inner 12 or 14 year-old and give him/her a jolt of pure, unadulterated, childish delight. One can feel del Toro’s passion and enthusiasm in every frame; and when we get swept away in that, it is a gorgeous and thrilling experience – as intended. "Boat bat" delivers.However, the "live-action anime" is far less effective when it comes to the human relationships. Particularly the one-foot-in, one-foot-out quasi sort of friends sort of love-story between Raleigh and Mako. It's classic boy meets girl stuff: They clash, he's impressed with her moxie and tough lady skills, with the weight of the world on their shoulders they must overcome their pasts and team-up to fight for the greater good, and just as his life is on the line, he "realizes that he has something to live for." In the right hands those tried and true tropes can create an entertaining B-story, but this one just doesn't work. By the time of the film's conclusion, their payoff feels entirely unearned.Hunnam plays it mostly straight, which is fine, but he doesn't necessarily infuse an already thinly-written character with much life. Kikuchi's performance, on the other hand, is occasionally perplexingly cartoonish. It seems clear that her exaggerated "little girl with big eyes" portrayal is a conscious choice, and likely a call out to some of the mecha anime that del Toro was referencing. However, her choices simply don't make sense for a living, breathing adult woman - nor for an adult audience.

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The pair don't have much natural chemistry, whether the intent was to portray a deep friendship or more, and are unfortunately unable to elevate the intermittently on-the-nose, exposition-heavy, and, in a few instances, uncomfortably simplistic dialogue. The majority of the events that take place in "the Shatterdome" (the area where the Jaegers and their pilots have convened to make one last stand) feels like wasted screen time, in fact. The initially hostile dynamic between maverick Raleigh and the Shatterdome's hot-shot pilot/leader of the pack Chuck Hansen (Robert Kazinsky) unfolds in a fairly predictable manner and is better observed in Top Gun. Chuck's relationship with his father Herc (Max Martini) has a bit more of an emotional punch, but that is mostly due to Martini's performance.The entire pilot storyline could have been trimmed down in favor of a few more monster vs. robot blowouts. We were away from that aspect of the film - the one that works - for about a half-hour on a plotline which wasn’t really needed. It takes far too long to reach what we all know is a foregone conclusion: Mako and Raleigh will indeed "drift" (merge minds) in order to pilot a once decommissioned Jaeger. The shoehorned in friendship (with what felt like an unnecessary romantic underdone) felt bloated and not nearly as evocative as Idris Elba’s simple drive to fight. In short, like Elvis says, "a little less conversation, a little more action" would have assisted the moment of the film. Elba, for his part, is fantastic and far and away the best part of Pacific Rim aside from the fighting beasts. He once again demonstrates that he's able to breathe vivid life into nearly any character, in any circumstance.Day's Dr. Newton Geizler and Perlman's Hannibal Chau are charming and funny enough, but again, seem more like characters out of a 1980's Big Trouble in Little China-type film than a modern-day sci-fi/action adventure. Burn Gorman is distractingly over the top as Geizler's lab partner/frenemy Dr. Hermann Gottlieb. Each nation's pair of pilots (or in one case triplet pilots) feels more stereotypical than the last. Team Russia are precisely what we imagine Dolph Lundgren's long-lost cousins from Rocky IV would look like: big, blond and Russiany.

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What's more concerning, though, is that we care as much about the fate of the characters that we've spent five minutes with as we do about those we've spent the majority of the film with: not a lot. There's just no real sense of weight or consequence; and the reason for the invasion defies logic and doesn't really gel with our understanding of basic natural history.Essentially, the issue is that the "this is what my inner little kid would love" aspect to this film only works when it's giant freaking robots fighting giant freaking monsters. The world creation is strong, but when we get into the human plotlines, it starts to feel as if this really is two hours of a cartoon meant for very small children rather than a film that has taken the essence of the films and anime that inspired it and translated them for a contemporary, adult audience. Again, it's clear that this is an homage to the mecha anime and fighting Kaiju movies that del Toro has such a deep passion for, and when that comes through it's glorious, but the intention of the film isn't always effective.The fight sequences are, as mentioned, often viscerally satisfying, shatteringly beautiful, and just as ass-kicking as you'd want, but even they are perhaps a touch too obscured at times. Del Toro paints a richly textured portrait utilizing every bit of what CGI imagery can offer. The final result is atmospheric and vivid, but the excessive use of rain and water sometimes blocks out the very thing we want to see - the Kaiju and the Jaegers going at it no holds barred. When the Kaiju vs. Jaeger battles work, Pacific Rim is a delight to behold, but those moments are sadly too few and are strung together with a story that would have been best served as a 22-minute Sunday morning animated adventure.

Roth Cornet is an Entertainment Editor for IGN. You can follow her on Twitter at @RothCornet and IGN at Roth-IGN