It feels like the majority of contemporary comedy films, whether insipid claptrap like American Pie and Wedding Crashers or superior fare like Knocked Up, have become afflicted with the same formulaic malady—in a word, they’re too plotty. These films take a potent comic premise, wring some laughs out of it, and then get mired down in their final acts trying to wrap up the characters’ story arcs with a straight face, though the audience might not really care. If anyone could get away with such a narrative transgression, you’d think it would be beloved TV and movie veteran Judd Apatow, who’s proven adept at creating sympathetic and endearing characters, from the teenage ensemble cast of Freaks and Geeks (many of whom reappear in the film) to the middle-aged celibate of The 40 Year Old Virgin. But here, though his skill at fashioning drama is satisfactory, it’s not really effective, particularly at a pregnant running time of 129 minutes. Knocked Up‘s about as swelled as its female lead’s enceinte belly.

Though, grammatically, Knocked Up‘s title might suggest that its central character is a member of the fairer sex (as in, she’s been knocked up!!), it’s primarily a film about men, the immature kind who need to learn to step-up when life, in all its unfairness, not only asks them to but demands it of them. That is, specifically, when they knock up a chick. Seth Rogen plays B[e]en Stone[d], a bejewfroed bongophile—with a framed Fear and Loathing in Las Vegas poster on his bedroom wall—who’s lucky enough, in a short-term sense, to get careerista Katherine Heigl drunk enough to initiate sexual congress; unfortunately, in a longer-term sense, it results in an accidental pregnancy. Deciding against having something that rhymes with shmusshmortion at a shmusshmortion clinic, Heigl chooses to keep her baby, and she and Rogen see if they can make an unlikely relationship work.

It’s a trial, as Rogen’s the epitome of Bill O’Reilly’s mythical stoner/slacker. A lot of sex- and drug-related shenanigans ensue, and Knocked Up‘s first third is hilariously fantastic, with a supporting cast of Apatow regulars and harmonious newcomers—each with an impeccable knack for comic delivery—hit all the right notes as they recite line after line of knee-slapping dialogue. Particularly effective are Rogen’s roommates, each playing if not themselves at least characters with the same names—Jay Baruchel, Jonah Hill, Jason Segel and Martin Starr; their rapport with Rogen and one another is marvelously natural, and Apatow’s got a real knack for goading on their improv. (Essentially, their scenes amount to watching five really funny guys hanging out and being really funny. Awesome.) Honorable mention goes to Kristen Wiig for her turn as a bitter television executive, whom she brilliantly downplays, and Apatow’s eldest daughter, whose confession to googling “murder” and speech speculating where babies come from are unexpected and priceless.

At times the film’s humor is a bit too pop- and tech-savvy in a way that’s sure to date it, not least of all in its humorous digression on Munich, a mediocre film destined, one can hope, to be forgotten. Also the best running gag, the guys’ teasing of Martin for his uncut hair and beard, surely won’t play as well for long. (“Was it hard when you changed your name from Cat Stevens to Yusef Islam?” someone asks him with deadpan casualness; someone else compares him to “Scorsese on coke,” a reference sure to light up the eyes and quake the belly of anyone who’s seen The Last Waltz.) But for the first half of the film, by and large, Apatow is flexing his directorial prowess as he takes a familiar sort of story and, for now at least, executes it perfectly, complementing the peripheries of the familiar romantic comedy center with vulgar and scatological raunch.

Ironically, however, it’s what makes Knocked Up a head above its multiplex competitors—its heart and attention to character—that curiously proves to be its undoing. When it gets too caught up in the ups-and-downs of Rogen and Heigl’s relationship, and the concomitant dramatic tension that amounts to “will they or won’t they?”—of course they will—it starts to get a bit tiring. Knocked Up is too funny to be convincingly dramatic; that is, it’s simply too funny to just redirect its focus from laughs to tears or pathos without feeling like it’s running out of steam. Nobody wants to be told to stop laughing and pay attention. Rogen is exceedingly likeable but not quite loveable, and all of the relationship-related hoopla between him and his girl, though presented with complexity and maturity, isn’t really anything new, and I’m sure it’s been done better. Propulsory plotting gets the best of the film at the expense of its comedy, whereas it’s in the latter that Apatow and the cast truly shine. (Though no one is by any means bad; for example, Heigl’s tearful breakdown at the “gynechiatrist”‘s office when she learns she’s pregnant is a laudably strong piece of acting.)

Knocked Up has a long list of good things going for it, but they unfortunately just don’t add up. A subplot involving Heigl’s sister, played by Apatow’s real-life wife Leslie Mann, and her diegetic husband (Paul Rudd) is a prime example; while providing a good many laughs through Rudd’s outstanding chemistry with Rogen, and a necessary example for Rogen and Heigl of how marriages based on child-rearing can go wrong, the lengths to which Apatow examines them feel excessive and unnecessary, the mark of a self-reflexive middle-aged man. (Which probably accounts for the film’s critical popularity.) Though Apatow’s love for his characters is what makes his work so likable, he loves them a bit too much, proving unable to leave them off-screen or on the cutting room floor to the ultimate detriment of the end-product; and, in a world where a DVD could be loaded with miles of outtake footage, why not sacrifice affection for tautness?

But I don’t mean to be unduly critical of Knocked Up because it is, admittedly, enjoyable and oftentimes a real aisle-roller, also managing to tend the delicate divide between sweet and sappy. I feel I should, though, counter the startlingly glowing praise the film has received from all corners of the country. All in all, Knocked Up is good, nothing more and certainly nothing less. Rent it, it’s funny.