Howard Hughes envisioned by Martin Scorsese and embodied by Leonardo DiCaprio in "The Aviator" is the ultimate can-do American, a ruthless, shoot-from- the-hip capitalist not afraid to gamble his fortune buying TWA or spend four years and a record-breaking budget to produce and direct his airborne World War I epic "Hell's Angels." He's a charming vulgarian, a lanky Texas shark with a voracious appetite for fame, fortune, aviation, beautiful women, the picture business--and the sheer pleasure of speed. Scorsese channels Hughes's hyperactive energy in his razzle-dazzle, high-flying biopic, his swooping, restless camera and virtuoso editing inducing a contact high.

But there's another side to Hughes--a streak of mental illness that stops this prince of perpetual motion in his tracks. An obsessive-compulsive with a lifelong phobia about germs, Hughes goes into the men's room at the Coconut Grove to clean a food stain off his shirt and becomes paralyzed, unable to exit because he can't bring himself to touch the doorknob and has to wait, terrified and humiliated, for someone to open it. When Hughes succumbs to bouts of madness, the movie goes still, as if stricken. "The Aviator" is built on these opposites: motion and stasis, a lust for life and a terror of it, teeming scenes of action and the stark spectacle of a frozen, paranoid man naked and alone in a room. It's a bipolar epic.

It's been a long time since Scorsese's made a movie this purely enjoyable. He revels in the glamour of old Hollywood, the rich Technicolor palette of Robert Richardson's cinematography consciously evoking a bygone era of filmmaking. John Logan's snappily written screenplay starts in 1927, when Hughes, using his inherited fortune to break into the movie business, begins filming "Hell's Angels." He founds Hughes Airways; sets speed records flying planes of his own design; outrages the censors flaunting Jane Russell's formidable cleavage in "The Outlaw." Best of all is his love affair with Katharine Hepburn, played with lip-smacking vivacity by Cate Blanchett, who captures her cocky insouciance to a T. In a cracklingly funny scene, she takes the rough-edged Hughes to her family's Connecticut estate for a combustible dinner-table clash between Yankee snobbery and Texas bluntness.

There's lots more in this long, generous movie--Hughes's public battles with Sen. Owen Brewster (Alan Alda), who's out to destroy him; his brush with death in a spectacular plane crash in Beverly Hills; an affair with Ava Gardner (Kate Beckinsale) and a power struggle with his arch rival Juan Trippe (Alec Baldwin), the owner of Pan Am. And the movie takes us up only to 1947. Scorsese was wise not to cram Hughes's entire life into one movie, but he pays a price: the wonderful parts don't quite add up. We're both surfeited and left wanting more. "The Aviator" is a movie-movie rendition of a larger-than-life man, but real life doesn't allow it to have a movie-movie ending.

DiCaprio is astonishing--wily, impulsive, paranoid, lurching from manic highs to crippling lows. I couldn't imagine him in this part but after seeing the movie, I can't imagine anyone else. Of course he's more boyish than the real guy, less craggily masculine. It doesn't matter: he suits Scorsese's design perfectly. This is, frankly, a somewhat whitewashed portrait. There's no mention of the man's racism and anti-Semitism, his flings with his male employees (if Charles Higham's biography is to be trusted) or the myriad others he used and discarded. This almost-great epic has one foot in legend: it's a vision of an American titan that could have sprung from the insides of Hughes's own obsessive, perfectionist head. It's an exhilarating--and sometimes chilling--place to be.