A somewhat shallow but certainly fond portrait of one of America's most celebrated anti-establishment folk heroes, "Steal This Movie" pays homage to Abbie Hoffman and his liberal ideals without really exploring what those ideals were all about.

Director Robert Greenwald seems to have made the film less for those who remember Hoffman and more for those who think of him mainly as some cool icon of the '60s.

But actor Vincent D'Onofrio pours so much of his soul into the role of the rambunctious, revered, reviled and persecuted populist agitator that his performance is just enough to forgive the movie for putting its politics on autopilot -- like a TV biography of a "great" politician might -- assuming the audience will take it as red that everything Hoffman stood for was noble and good without going into depth about his philosophies.

D'Onofrio's deep-thinking, yet sauntering stoner-style portrayal captures Hoffman's tenacious passion for freedom and peace, and his psychological problems, which were aggravated by a lifetime of persecution by the duplicitous conservative government of the day. As the film opens Hoffman has already been underground for "five years, 17 cities, and 63 jobs" -- a fugitive from his conviction for inciting a riot as the leader of the Chicago Seven, the group of Vietnam War protesters whose huge rallies during the 1968 Democratic National Convention led to brutal tear-gassing and baton-beatings by police.

Hoffman's life before the trial -- from his clean-cut youth registering black voters in the South to his ever more theatrical anti-government protests throughout the late '60s -- is told in "Citizen Kane" style flashbacks to a journalist interviewing Abbie's wife Anita (Janeane Garofalo), his lawyer Gerry Lefcourt (Kevin Pollak) and others.

Then the story picks up in the late 1970s as Hoffman begins to emerge from hiding under an assumed name, becoming a high-profile environmentalist trying to protect the St. Lawrence River.

The emotional crux of the story is how Hoffman's tormented psyche is affected by years of relentless harassment and smear campaigns orchestrated against him by Hoover's FBI. Director Greenwald exploits heavily the fact that he was a stranger even to his own son until 1980, but he skirts Hoffman's character flaws, like the marital strife that arose from his becoming attached to another woman (Johanna Lawenson, played by Jeanne Tripplehorn) during his years in hiding.

But even with its shortcomings, "Steal This Movie" is a candid and entertaining biography. Greenwald employs an array of newsreel and recreation techniques to drop the audience convincingly into the chaos of the Vietnam era and often comes up with other clever ways to make you feel a part of the story, like when he introduces an intimate moment between Abbie and Anita by listening in on them through the FBI's surveillance equipment. The vast soundtrack of perfectly-chosen period tunes really helps the atmosphere, too.

But the picture is most enjoyable because of the amazing ensemble of well-cast actors giving faultless performances as real people. Tapping D'Onofrio as Hoffman was a masterstroke, as the actor captures perfectly the essence of his free spirit. (He's 100 times better here than as the psycho killer in "The Cell," also released this week).

Garofalo gives what is easily her best and most character-embracing performance yet as the loyal, intellectual and liberated Anita, who spent most of Hoffman's years in hiding fending off press and FBI entrapment while trying to make ends meet for her and her son.

Stew Albert is played by uber-dude Donal Logue ("The Tao of Steve"), Jerry Rubin is played by indie chameleon Kevin Corrigan ("Buffalo '66), and Tom Hayden (now a California senator) is played by his own son, Troy Garity. You don't get much more authentic than that.

I'm too young to remember Abbie Hoffman in his prime, so I can't speak to the movie's absolute veracity, but it definitely made me feel like I knew the man by the time the credits rolled.