Dark familial comedy "Peep World" is acidic yet sympathetic, a balancing act on the parts of director Barry W. Blaustein (2005's "The Ringer") and debuting screenwriter Peter Himmelstein that keeps the film from ever becoming either too snarky or too sentimental. It is, however, at least twenty minutes too short. In a day and age when movies are typically bloated and don't know when to quit, here's one that doesn't realize it should have gone on—or at least brought a little bit more development to what there already was on display. Still, a lot of honest notes are hit as the broader bits of humor mingle with its seriocomic portrayal of people joined by blood and the nagging hang-ups they no longer can keep hidden out of sight.

29-year-old Nathan (Ben Schwartz), the baby of the Los Angeles-based Meyerwitz clan, has just released an exposé slimly disguised as a novel about his family's real-life dirty laundry. Naturally, not everyone is thrilled. Eldest brother Jack (Michael C. Hall) is an architect about to become a father, lose his company, grow tired of always being the "good" one in his family, and be discovered by wife Laura (Judy Greer) for his porn addiction. Black sheep Joel (Rainn Wilson) is a ne'er-do-well lawyer who has finally passed his BAR exam after numerous fails and begun to see police officer Mary (Taraji P. Henson). Struggling actress-singer-songwriter Cheri (Sarah Silverman) is so outraged by her brother's book that she's decided to sue him. As for Nathan, his book tour hits a slight snag when he makes the wrong decision to visit a doctor about his premature ejaculation problem right before one of his appearances. All of these people and more are about to reunite for their judgmental real estate magnate father's (Ron Rifkin) 70th birthday dinner, and it's not going to be a pretty sight.

Narrated by Lewis Black with the all-knowing God-like presence of the voiceover used in 1999's "Magnolia," "Peep World" can attest to having a terrific ensemble cast, not all of them written as fully as they could have been but every one of them a valuable part of the film's pleasing whole. Set within an 18-hour time frame, the picture is more probing snapshot than thorough biography of a family consisting of an insensitive father, a remarried mother who has been quiet for far too long (a low-key Lesley Ann Warren), and four grown siblings whose actual problems stem from their struggle to make proud a man who never viewed what they did as good enough. The script is lined with zingers—the revelation that Cheri slept with the entire cast of "Tony n' Tina's Wedding" because she liked the show so much is a hoot—but rooted in the poignant truths of its dysfunctional family. They may be testy and short-tempered for any number of reasons, but aside from patriarch Henry, they're all exceedingly easy to be around and grow to like.

In a uniformly strong line-up of performers, Sarah Silverman (2006's "School for Scoundrels") stretches nicely in a meatier, more down-to-earth role than she's accustomed to as irate sis Cheri, while Judy Greer (2010's "Love and Other Drugs") as Jack's wife Laura, Taraji P. Henson (2010's "The Karate Kid") as Joel's girlfriend Mary, and Kate Mara (2010's "127 Hours") as Nathan's admiring PR rep Meg are three testaments to how top-notch actors can transform standard, underwritten supporting parts into characters who feel textured and real. The viewer yearns to learn more about them than what they do, the script by Peter Himmelstein solid but overly streamlined.

"Peep World" all boils down to the ensemble's third-act joining-together at a ritzy restaurant for Henry's annual birthday dinner. Playing on its own like a compulsively watchable chamber piece, this extended sequence enthralls, amuses and stings with insight and veracity. From Jack's confession about where he stands in his career and personal life, to Nathan's discovery that his father hasn't even taken the time to read his novel, to mother Marilyn's umpteenth failed attempt to speak her mind, to a remark made likening Nathan's tell-all book to "a bad photograph, or hearing yourself on a tape recorder for the first time," to Cheri's chime-in that, yes, she still plans to sue, the finale of "Peep World" is mesmerizing. It's also, finally, anticlimactic, drawing to a close so abruptly and patly that one can't help but acknowledge how much better it could have been with some fine-tuning and nourishing of the ripe material. On the one hand, at least the film doesn't overstay its welcome. On the other hand, it doesn't match what it's clearly capable of. "Peep World" is an entertaining slice of salty life, but ultimately just what its title suggests: merely a peep into a world with greater potential.