"Guardians of the Galaxy" isn't as widely known an entity as fellow Marvel-Comics-turned-big-screen-franchises "Iron Man," "Captain America" and "Thor," but that is destined to change with the release of writer-director James Gunn's (2011's "Super") vivaciously crowd-pleasing space adventure. Based on the 2008 comic reboot by Dan Abnett and Andy Lanning (which, in turn, derived from a 1969 incarnation with different characters), the film separates itself from the pack by not really feeling like an origin superhero story at all. Instead, Gunn and co-writer Nicole Perlman have conceived of a full, vivid tale, one that has room to develop into a multi-picture saga but could just as confidently stand on its own. More important still, "Guardians of the Galaxy" displays an irresistible personality that does not appear to be stuffily beholden to the source material. Spending time with the picture's ragtag team of unlikely intergalactic warriors proves an irresistible two-hour proposition.

When Peter Quill (Chris Pratt) was a young boy, he was abducted by extraterrestrial thieves and smugglers on the same night his beloved mother (Laura Haddock) passed away from cancer. Twenty-six years later, he roams the star system under made-up alias Star-Lord, a legendary outlaw in his own mind with only an unopened letter from his mom and a mix tape of awesome '70s tunes to remind him of his life on Earth. When one of Peter's scavenging expeditions puts him in possession of a mysterious silver orb, he initially does not realize its sheer power. Working to do the vicious Thanos' bidding, Kree radical Ronan (Lee Pace) desperately wants to snatch the object. Using it against the cosmos, however, could spell cataclysmic doom for the peace-driven people of planet Xandar. Peter is not expecting to meet friends and trusted allies, but this is what ultimately happens when he is paired with other scrappy outsiders—the green-skinned Gamora (Zoe Saldana), longing to shed her torturous years of violent conditioning; the burly Drax the Destroyer (Dave Bautista), looking to avenge his murdered family; Rocket (voiced by Bradley Cooper), a cocksure genetically engineered raccoon mercenary, and Groot (voiced by Vin Diesel), a good-natured humanoid tree—to put a stop to Ronan's plan.

"Guardians of the Galaxy" opens with a poignant 1988-set prologue and an attention-grabbing hook prior to not only the opening credits, but also the rousing Marvel studio logo. So far so good, but it is when Redbone's "Come and Get Your Love" washes over the soundtrack via adult Peter's trusty Walkman that director James Gunn adamantly confirms his position as more than just a work-for-hire filmmaker tasked to emulate the comics-based box-office hits that have gone before it. Exhibiting a frisky sense of humor and a poppy mischievousness without losing sight of its sometimes quite sensitive heart underneath, "Guardians of the Galaxy" plays more like a winky-faced space opus than conventional superhero fare. This embracing of individuality goes far in juggling a cast of protagonists who are all misfits in their own ways, consciously turning their backs on what is expected of them so that they can be who they truly are.

Chris Pratt (2013's "Her") has been enjoying a steady career for several years, seguing between supporting character roles in film and as a regular on TV's "Parks and Recreation," but his standout work as Peter Quill/Star-Lord is very clearly and specifically destined to promote him to the Hollywood A-list. Pratt is a handsome guy, but it is his affable, genuine, energetic, identifiable nature that multiplies his attractiveness. The viewer comes to believe in Peter while gaining an increased admiration for the actor playing him, and Pratt is just as affecting in his emotional scenes as he is in delivering a self-effacing quip. As Gamora, Zoe Saldana (2013's "Star Trek Into Darkness") is winningly paired with Pratt, her trained assassin yearning to break away from Ronan's psychological hold and do instead what she knows is right. Gamora's chemistry with Peter is pitch-perfect, coming on lightly but amusingly as she sizes this strange man up and takes the first steps to letting down her defenses. When he plays for her Elvin Bishop's "Fooled Around and Fell in Love"—possibly the first earthly music she has ever heard—it is a sweet moment, even if she refuses to dance. "I am not one to succumb to your pelvic sorcery," she says.

Don't be fooled by Dave Bautista's (2013's "Riddick") size; he may be big, but the professional WWE-wrestler-turned-actor is not dumb. Without seeming forced, Bautista conveys all of Drax's pain and fury over losing his wife and daughter. Bradley Cooper (2013's "American Hustle") and Vin Diesel (2013's "Fast & Furious 6") bring their own layers to photorealistic digital effects creatures Rocket and Groot, and they only have their voices (and an unusually astute script) to work with. Because Diesel's role calls for him to predominately repeat the same three-word line of dialogue throughout ("I am Groot!"), it is especially surprising that one grows such an attachment to this walking, barely talking tree. For his part, Cooper's Rocket steals his scenes, a man in a raccoon's body whose outward confidence masks an underlying insecurity over who he is and the genesis of his creation. As central on-screen villain Ronan, Lee Pace (2013's "The Hobbit: The Desolation of Smaug") must be great because he is entirely unrecognizable playing the heavy of the piece. Benicio Del Toro (2012's "Savages") pops up as the enigmatic, bleach-crazed The Collector, but is in and out too briskly, while Glenn Close (2011's "Albert Nobbs") and John C. Reilly (2011's "We Need to Talk About Kevin") are noticeably underused as Xandar's trusted council head Nova Prime and Corpsmen Dey. Close and Reilly are far too gifted and recognizable to be put in these forgettable glorified cameos.

"Guardians of the Galaxy" looks smashing and is bursting with all the fun and action one will be expecting from a $170-million extravaganza that features a palpable dramatic core but doesn't weigh itself down with a preponderance of seriousness. The overstuffed plot is on the convoluted side, tossing so many fictional planet names and characters at the audience that, for a time, it can get overwhelming. James Gunn isn't one to spoon-feed, however, the director relying on his visuals, his performers, and his storytelling prowess to carry the viewer through his fantastical sights and interstellar conflict. It is gratifying to consider how very different in tone and sensibility "Guardians of the Galaxy" is to its brethren, the film, above all, a love letter to the joys and connecting forces of music (Blue Swede's "Hooked on a Feeling," Rupert Holmes' "Escape (The Pina Colada Song)," The Five Stairsteps' "Ooh Child," and, best of all, The Runaways' "Cherry Bomb" have their moments front and center). These chestnuts, once his late mom's favorites, accompany Peter on a journey that ultimately has just as much to do with finding closure and saying good-bye to loved ones as it does saving the world. Of all of Marvel's many Phase I and Phase II projects tackled since 2008's "Iron Man," "Guardians of the Galaxy" is, to date, the most alive with imagination and wonder.