Grade: C-

The title is ironic, of course. “Gigantic” is a little movie. But not, unfortunately, a modest one. It wears its small-scaled quirkiness like some major medal of honor, and is weighed down by a strenuous effort to seem meaningful without actually saying anything.

The central character is Brian Weathersby (Paul Dano), a lanky fellow working as a salesman for an ultra-expensive mattress firm in NYC who’s so laid-back and withdrawn that he seems somnolent himself. Soon after an unfortunate run-in with a silently menacing homeless man (Zach Galifianakis) that leaves him with a big black eye, Brian meets roly-poly Al Lolly (John Goodman), a voluble, tough-talking customer with a bad back, and his daughter, the free-spirited Harriet (Zooey Deschanel), who comes on to him pretty fast. Before long things between him and her get serious, with Al looking on like a burly bear while making sometimes snide, sometimes supportive remarks as the dour young guy follows her around with his perpetually hangdog expression.

Brian’s docility results, at least partially, from the fact that he has to put up with a demanding family background: he’s got siblings far more successful than he, and his parents (Ed Asner, Jane Alexander) are so old that they’re often mistaken for his grandparents. Dad, moreover, is a colorfully crusty old coot with a habit of blurting out uncomfortable observations at inopportune moments. And did I mention that Brian is jumping through bureaucratic hoops trying to adopt a Chinese child, though since he’s unmarried the likelihood of his being successful is slight?

There’s considerable potential in some of these details, but Adam Nagata and Matt Aselton don’t take much advantage of it, content instead to amble through a succession of vaguely goofy and ultimately inconsequential episodes that float from the memory as soon as they’re over, trying to paper over the thinness with extravagantly off-the-wall dialogue. There’s no weight to the relationship between Brian and his family (as witnessed by the offer by one of his brothers to put him in touch with a Chinese client who might be able to smooth the adoption process), and not much more between him and Harriet either, until their ultra-cute match-up is threatened by her unease at the prospect of his actually getting a child. The most incomprehensible moments, however, involve that aggressive homeless fellow, who shows up a second time to give Brian another thrashing. What his significance might be is never made clear—unless it’s the randomness of life—and the second episode, when he seems to suddenly vanish like a phantom, makes no sense at all.

Even one who’s been a fan of Dano since his striking debut in “L.I.E.,” moreover, may be forgiven for thinking that this is far from his best work. It must have been Aselton’s choice to have him play Brian so lifelessly, but it doesn’t make the character endearing or even interesting—just dull. And with Deschanel doing her usual ditzy shtick and Goodman and Asner chewing up the scenery all around him, Dano looks even wimpier.

Technically “Gigantic” is more than adequate, with good widescreen photography by Peter Donahue and a generally skilled use of location. But by the close you’ll probably feel that you’ve been inundated by a tidal wave of affectation. The protagonist might be so laid-back that he virtually disappears, but the picture itself tries much too hard—and stumbles.