There have been so many stomach-churning mass-market Yuletide movies in recent years—films that are either dumbed-down beyond belief or send out the wrong message—that expectations were admittedly not high walking into "Four Christmases." Nightmares about 2004's "Christmas with the Kranks," 2006's "The Santa Clause 3: The Escape Clause" and "Deck the Halls," and 2007's "Fred Claus" and "The Perfect Holiday" still haunt my sleep. With a few tweaks, this latest holiday comedy could have gone the way of all those aforementioned disasters, and sometimes does come close to straddling that fine line. Still, director Seth Gordon (2007's acclaimed video game documentary "The King of Kong") has some honest points to make about familial dysfunction, and sneakily works them in between broad comic set-pieces.

Kate (Reese Witherspoon) and Brad (Vince Vaughn) are a happy San Francisco-based couple who pride their three-years-and-counting relationship on their personal independence and avoidance of all things having to do with marriage and procreation. With Christmas approaching, their plan (as it is every year) is to go on vacation in lieu of spending time with their families. When a heavy fog cancels all flights and they find themselves being interviewed live on the news, they have no choice but to bite their tongues and head from one of their parent's homes to the next. Madcap hilarity ensues, to be sure, but so does a bit of soul searching for Kate and Brad, as the day leads them to reassess what they want out of their relationship.

"Four Christmases" has about three screenwriters too many (the script is credited to Matt R. Allen, Caleb Wilson, Jon Lucas and Scott Moore), and the film's seasonal atmosphere is lacking with only a few Christmas songs and a decidedly non-wintry San Francisco location. Whose bright idea was it to set this in Northern California? Against these odds and others—director Seth Gordon pushes too hard in spots to create zaniness and instead ratchets up monotony—"Four Christmases" gradually works itself into the viewer's good graces.

For just about every would-be funny moment that falls flat, there are just as many that startle with their sharp sense of timing and wit. The movie is not afraid to go for the throat or be acerbic, as when Brad's set-in-his-ways father (Robert Duvall) says, "I don't want to talk ill about your mother on Christmas, but she's a common street whore," or when sister-in-law Susan (Katy Mixon) describes to Kate in graphic detail the effects of breastfeeding on the nipples. An obvious jab at evangelical religion and the birth of Jesus, a heated game of Taboo with Brad's mother (Sissy Spacek) and family that is as amusing as it is truthful, and a humiliating revisiting by Kate's mother (Mary Steenburgen) and sister Courtney (Kristin Chenoweth) of her painful childhood follow.

The characters in "Four Christmases" are not always likable, and they're not meant to be, which is sort of refreshing. While some bonds are strengthened—Kate has a heart-to-heart with her caring father (Jon Voight), and Brad has a third-act conversation with his own dad, a man he has never gotten along with, that is unexpectedly poignant and perceptive—others probably never will. A scene where Kate asks her mom if she can talk to her, and her mom cruelly infers that she has no interest in whatever she has to say, is stingingly brutal, and yet authentic to the way some people are self-involved and ignorant to others' emotions. Even when painting a dark picture of bloodlines, the film offers up rays of hope by the conclusion. Courtney, Kate's sis, shows a human side that she hadn't earlier in the day, and the way Kate's divorced parents are able to come together with their respective significant others in tow in order to keep the family together for the holidays is quietly uplifting.

Whether the rumors of on-set tensions between leads Reese Witherspoon (2007's "Rendition") and Vince Vaughn (2006's "The Break-Up") are true or not, they are engaging and believable as Kate and Brad. Kate's growing desire throughout the day to have children of her own seems a little forced, especially since the kids on display are written as terrors, but her interactions with Brad and the support they show each other are that of a healthy onscreen partnership. The rest of the ensemble is extensive, but there are a few standouts. Robert Duvall (2007's "We Own the Night") takes his role as Brad's stubborn dad to deep dramatic places you'd expect to find in Oscar fare. A surprisingly buff Jon Favreau (2004's "Wimbledon") disappears into the part of Brad's overly aggressive fitness trainer brother Denver. Katy Mixon (2006's "The Quiet") is a fearless comedic force as Denver's baby-making wife Susan; her first line, mangling the pronunciation of "hors d'oeuvre," couldn't be better. Sissy Spacek (2007's "Hot Rod") has fun as Brad's mother, but is out of the picture too quickly. By comparison, Mary Steenburgen (2008's "Step Brothers") wears out her welcome as Kate's mother simply by essaying such an unpleasant character. And what, pray tell, is the brilliant and underrated Carol Kane (2005's "The Pacifier") doing in the nothing role of one of Kate's cougar aunts? She is in a handful of scenes, but has three lines, tops.

"Four Christmases" concludes on a sweet but not sugary note, or would have were it not for a "One Year Later" epilogue that is unnecessary and pandering. Nevertheless, the film does a nice job overall of juggling comedy with gravitas, and silliness with a love story that hits the mark on all the little quirks and layers of a couple's personal relationship. Though flawed, "Four Christmases" knows enough about families that even the few caricatured portraits derive from real places. Here, then, is a holiday comedy that goes down with ease, avoids insulting one's intelligence, and doesn't leave you wanting to shoot your eye out with a Red Ryder.