Having spent almost three straight days in Hall H last July sorting through the wheat and the chaff of the geek world, I admit that I was one of the first in line to champion the preview footage from Kick-Ass as a highlight of the 2009 San Diego Comic-Con because, well, it kicked ass. It seemed tailor-made for comic book fans, exploiting their fantasies about becoming caped avengers, while at the same time offering enough foul-mouthed, visceral action to stop even the most jaded moviegoers in their tracks. And of course it featured Chloe Moretz' Hit Girl, a potty-mouthed preteen destined to become a pop culture lightning rod thanks to her equal dexterity with four-letter insults and flying jump kicks.

Unfortunately, as a full-length film, Kick-Ass is a great comic book come to life, but not much else. A faithful recreation of the rhythms of episodic funny-paper storytelling, Matthew Vaughn's adaptation of Mark Millar and John Romita's 2008 series gives greater scope to the set pieces shown in clips and trailers, but never quite finds enough cohesion or dramatic clarity to become a fully satisfying film.

Aaron Johnson plays Dave Lizewski, a sexless, comics-obsessed teenager who spends a hundred bucks on a scuba suit and decides to become a superhero named Kick-Ass. His first effort to take out a couple of car thieves earns him a trip to the hospital, but he recovers and realizes that his rehabilitation has given him the real-world equivalent of super powers, including bones now protected by steel rods and nerve endings that don't respond to pain. After protecting a young man from a severe beating -- within eyeshot of a passerby with a camera phone -- Kick-Ass quickly becomes a local hero. But after he unsuccessfully asks a drug dealer to stop pestering his dream girl, Katie (Lyndsy Fonseca), Aaron realizes he's neither the only self-made hero on the streets, nor the most qualified: Hit Girl (Moretz) and her partner Big Daddy (Nicolas Cage) have hardware and training that he's only seen, well, in comic books.

Hit Girl and Big Daddy have bigger plans for crime-fighting, in particular shutting down a local kingpin named Frank D'Amico (Mark Strong). But when D'Amico's son Chris (Christopher Mintz-Plasse) dons a cowl and decides to become a vigilante as well, Kick-Ass and his colleagues are forced to confront the harsh realities of what it takes -- and what it costs -- to play superhero.

The good thing about the above synopsis is also the film's biggest shortcoming -- namely, that this scarcely scratches at the surface of what takes place over the course of the film's overlong two-hour running time. Indeed, for a film called Kick-Ass and supposedly about Kick-Ass, his story is basically told within the first 45 minutes to an hour, and the rest is devoted to the larger universe of "real-world" superheroes that his role-playing fantasy inspires. In that sense, the movie's like a full-fledged trilogy of franchise developments condensed into a single entry, which would be fine and even interesting if there was an arc that sustained the title character through each of its installments, or here, acts.

But director and co-screenwriter Vaughn's affection for the world on the page doesn't easily satisfy the structure of a film, even if again it seems faithful in its preservation of the chapter-by-chapter storytelling of single-serving comic books: perhaps there can be "lesser" chapters in a print series where there are dozens of issues -- fun detours or frivolous adventures that digress from the main character's hero journey. But here, Aaron seems to learn nothing from his experiences, nor build upon them anything except a vague sense of self-worth, which again is essentially fully resolved during the first half of the movie.

Meanwhile, the relationship between Hit Girl and Big Daddy, not to mention Frank D'Amico and his son Chris, gains an emotional depth as the film moves forward, and really gives Kick-Ass its most effective moments. Truly, the sentiment of these relationships are actually where the film's strengths lie; Vaughn manages to create that heightened sense of reality much like he did in Stardust, but keeps the feelings of the characters grounded in a semblance of believability. We do sincerely empathize with the motivations of Big Daddy, or understand Chris' desperate efforts to win his dad's approval. But the set pieces are so fully and elaborately realized -- indulged, even -- that the undercurrent of feeling we share with the characters evaporates before it can really permeate the less evocative scenes and inject the whole film with a compelling sense of emotional substance.

Of course, those set pieces are primarily what will bring in viewers, especially since their juiciest moments have been lovingly revealed in previews and clips. But they aren't especially well-shot, or at best poorly paced; during one showdown Hit Girl spends at least five minutes behind a kitchen counter while her opponents figure out what to do next, and to no great dramatic effect. The film's staccato rhythms only further highlight the lack of coherent storytelling and continuous character development, so that by the time our heroine is cowed and wonder who will help her, we're more interested in seeing literally anything happening than something that specifically rewards our patience in this particular scenario.

Plus, even having seen only the Comic-Con footage from last summer and largely skipped the interstitial clips and promotional materials, I hoped I hadn't seen everything it had to offer, but was disappointed to discover there was little more to explore in the finished film. Once the novelty wears off of watching a 12-year-old girl impale adversaries while calling them "*ssholes" or worse, there's nothing deeper or more meaningful within Vaughn's vision to sustain subsequent viewings. The closest analogy I can think of with Kick-Ass is that it's a visceral (as opposed to logical) companion piece to a film like Memento or The Usual Suspects, where the style and energy is spectacular and striking the first go 'round, but it's not only the concept, the "hook," but the execution, and finally, the cumulative effect that prompts you to return to the material again and mine what deeper intricacies may exist.

The difference between Singer and Nolan's films and this one is that they were built on ideas that were both entertaining and intellectually involving, while Vaughn's forgoes the latter in pure unadulterated favor of the former. In which case, yeah, Kick-Ass lives up to its name and then some, but is there anything else to it? I don't think so, which is why I definitely felt afterward like my ass had been kicked, but I'd have preferred if my mind was even remotely roused at the same time.