The title character of "The Informant!" loves to talk. He doesn't know when to stop talking, as a matter of fact

That turns out to be a crucial character flaw. And it's a nearly crippling flaw for the film itself.

This fact-based, '80s-period comedy-drama is just too talky for its own good. In fact, a few audiences might be put off by the film's constant flow of dialogue — which includes quite a bit of voice-over narration.

(Be warned that some of that dialogue consists of R-rated profanity and other such language as well.)

Yet it's hard to completely dismiss the film, which sneaks in a few sly messages about corporate malfeasance and the American justice system. And if nothing else, it represents another impressive step forward in the career of Matt Damon, who keeps re-inventing himself as an actor.

He added a few pounds as well as a cheesy moustache to play Mark Whitacre, a former agri-business executive who was the subject of Kurt Eichenwald's best-selling book of the same name.

In this version of events, Mark and his wife, Ginger (Melanie Lynkey), suspect that the corporation he works for may be part of a worldwide price-fixing scheme.

So he agrees to aid in an FBI investigation. The overzealous whistle-blower even tries to befriend the investigating agents (Scott Bakula and Joel McHale).

Director Steven Soderbergh tries too hard to force his tone on the material. There's already enough goofiness here. We don't need an overly wacky score (courtesy Marvin Hamlisch) nor do we need the cutesy stylistic touches to tell us this isn't meant to be taken seriously.

Soderbergh also populated his supporting cast with comedians and comic actors. McHale (TV's "The Soup"), Patton Oswalt, Paul F. Tompkins, Scott Adsit (TV's "30 Rock"), Tony Hale and the Smothers Brothers all show up at various points in the film.

But it's Damon who gets most of the laughs. His character's look and wardrobe may be unflattering to Damon, but he's convincing and is surprisingly sympathetic.

Of course, it helps that he's been paired with Lynskey (TV's "Two and a Half Men"). She's also quite good as a housewife who remains steadfast despite the chaos going on around her.

"The Informant!" is rated R and features strong sexual language (profanity, slang and other suggestive talk), other off-color humor and references, derogatory language and slurs, and brief drug references (mostly industrial chemicals and supplements). Running time: 108 minutes.

e-mail: jeff@desnews.com