The flimsy but funny enough "Our Idiot Brother" makes a pact with its audience. In time-honored movie tradition, it will teach us something that's not especially true, but we'll all agree upon it for the sake of an unbothered evening out.
In this case, the lesson is that our lives would all be better with a moronic screw-up around to shine a light through our denial and illuminate our foibles. The idiot in question is Ned Rochlin (Paul Rudd), a hippie-dippy farmer in upstate New York who's sent up the river -- in the film's opening sequence -- when he sells pot to a uniformed police officer. So, y'know, he's not especially bright.
But the larger point is that Ned is a trusting optimist, his naivete being a sign of his unselfish (nay, giving) good nature. Styled like Jesus and defaulting to a beatific smile, Ned is hard not to like. Unless you're his girlfriend, Janet (Kathryn Hahn), who kicks the parolee off their farm and bogarts his dog Willie Nelson. Or one of Ned's sisters, who long ago tired of lending him money and feigning tolerance at his loser lifestyle.
When Ned can no longer stand to sleep in his old bed under the smothering watch of his wine-swilling mother (Shirley Knight), he makes the rounds of his reluctant sisters' homes, his loose-lipped lack of an internal censor causing short-term damages. First, he stays with Liz (Emily Mortimer) and her documentary-filmmaker husband, Dylan (Steve Coogan), becoming the governess/jester to their 7-year-old son River (Matthew Mindler).
Failing that, he crashes with Miranda (Elizabeth Banks, channeling Parker Posey), a ladder-climbing Vanity Fair writer, causes more problems, and moves on to bisexual sis Natalie (Zooey Deschanel) and her lawyer girlfriend, Cindy (Rashida Jones).
Written by Evgenia Peretz and her husband David Schisgall, and directed by Lemonheads bassist Jesse Peretz, the movie neither underachieves quite so much as its hero, nor works very hard. Beautifully played by Rudd, Ned evokes "The Big Lebowski"'s "Dude" with his stupid-like-a-fox drifter zen (his plans don't stretch beyond renting from his ex "the goat barn on the back 40").
The movie he inhabits, though, is unmistakably "Little Miss Sunshine"-y, complete with a cute tyke who's got it more together than the adults. Approaching the movie with the understanding that it's going to be a sunny sitcom of family dysfunction will help it along, and an ensemble with impressive chops certainly bolsters the proceedings.
The suggestion that it's not holy-fool Ned who has something to learn may rankle some, but at least "Our Idiot Brother" takes the character seriously enough not to coat him in Teflon: He knows he's a screw-up and cycles through embarrassment on the way to a burst of frustration (albeit triggered by one too many sororal slights).
More bothersome is the neatly gift-wrapped resolution, with the sisters concurrently emerging from their blind spots. Though one earlier claims, "A family is a very precarious thing," the opposite proves true. Just nod and smile ... remember the pact.