MOVIE REVIEW: "The Guilt Trip" 

It's one of those unfortunate but unavoidable facts of life that even the most responsible, mature, put-together adult can, in an instant, regress back into the role of petulant child when in the company of their parents for any extended period of time. It might take just a look, or a single judgmental comment, but inevitably, the fragile house of cards that is adulthood will come crashing down.

This is a phenomenon that "The Guilt Trip" understands all too well. The new family-friendly comedy from director Anne Fletcher ("27 Dresses," "The Proposal") is about a son (a tame Seth Rogen) and his mother (a surprisingly well-cast Barbra Streisand) on a cross-country road trip together. As a result, the central mother/son relationship is well-defined and often relatable. Sadly, the movie built around that relationship is a shapeless, largely unfunny, mess.

Struggling inventor Andrew (Rogen) has a secret motive when he extends the invitation to his mother, Joyce, to accompany him on his drive from New Jersey to Las Vegas as he meets with various corporations to pitch them the new all-natural cleaning product he's developed. Inspired by a conversation he has with his widowed mother, in which she reveals that before she met Andrew's father she was deeply in love with another man, he decides to add an extra stop in San Francisco to try and reconnect his mother with her long-lost soul mate. As much as his overbearing mother may infuriate him, Andrew still loves her and doesn't want her to spend the rest of her life alone. Though skeptical about why her son would voluntarily spend eight days with her in a car, Joyce jumps at the chance for some family bonding time. The odd couple set off on the road, and wacky-ish hijinks ensue as they fight, argue, and eventually learn from one another.

While the film is sporadically amusing, it never revs itself up enough to reach the level of laugh-out-loud funny. Rogen and Streisand themselves are funny as a duo, and work together convincingly as mother and son. There's a tenderness around the relationship at the film's core that remains likeable. But it's worth noting that I laughed more during the clips that run over the film's end credits, where the two actors ad-lib and play off of one another, than at any exchange that made its way into the finished film.

Rogen works well as the mild-mannered straight man of the film, apparently having no qualms about ceding most of the spotlight to his co-star. The film's screenplay is credited to Dan Fogelman ("Crazy, Stupid, Love"), supposedly based a real-life road trip he took with his mother, but I couldn't help wondering what this pair of actors would have done with a snappier, wittier script. There's too much time spent setting up situations — a stop at a strip club; Joyce deciding to enter a food challenge; gambling in Vegas — and most fail to provide any sort of payoff. One compliment I can pay it is that there isn't too much of a reliance on the Jewish mother schtick. It's there, to be sure, but it's not overdone so that it grows obnoxious.

The talents of the cast are also ill-served by Fletcher's flat, bland direction; her previous box-office hits relied mostly on the charms of their stars (less so "27 Dresses," I guess — I don't know that there's anyone who actually finds Katherine Heigl charming). I wish I knew who made up the rule that American comedies aren't allowed to have any sort of style, so I could knock some sense into them.

Still, the movie will likely be a hit, coming out during the season when families are looking for innocuous entertainment that won't be painful for any single member to sit through. I suppose the movie meets the rather low bar it sets for itself in that, when I paid my mother a visit just after watching the film, I realized that I was kicking myself for not bringing her along to the movie with me. Instead I just told her that there was a movie out in theaters now that I thought she'd really enjoy.