Terry Gilliam has always had a star-crossed career. His magnum opus, "Brazil," was sliced-and-diced and essentially neutered when it hit American shores. The problems he ran into shooting "Man of La Mancha," a film he never finished, have been widely documented. "Tideland," his last film and his most personal movie to date, was (rightly) savaged by critics and ignored by most audiences. And during his latest film, "The Imaginarium of Doctor Parnassus," leading man Heath Ledger died during shooting.

Of course, that means "Imaginarium" has to be considered with that in mind, doesn't it? Because Gilliam's solution, having Johnny Depp, Jude Law, and Colin Farrell to step into Ledger's shoes for various sequences, wasn't a choice borne out of anything but necessity. Essentially, it's a conceit that you have to decide if you're able to forgive as an audience member, but since you know the history behind the film and Ledger's death, it's one that's fairly easy to do.

So, that said, "Imaginarium" is fascinating. But it has flaws. There are problems. It has some holes. But they generally don't feel as though they exist because of Ledger's death. It's also a truly unique and often ingenious film, the sort of picture that could only come from Gilliam. Christopher Plummer is the titular doctor, an ancient, wizened creature traveling around England with a rickety sideshow, accompanied by his daughter, Valentina (Lily Cole), the diminutive Percy (Verne Troyer, best known for playing Mini Me in the "Austin Powers" franchise), and Anton (Andrew Garfield), a street urchin the good doctor has taken in who has been in love with Valentina for years. They show they present is barely a show at all, unless they can convince an audience member to enter the Imaginarium itself, a portal that puts them deep within a world of their own psyche, and one where they must choose between Doctor Parnassus (who may, or may not be God) and Mr. Nick (Tom Waits playing a character who may, or may not be, the Devil). Go with Parnassus, you are essentially reborn. Go with Nick—the exceedingly tempting Nick—and you never come back out.

All of this goes along nicely, except that Valentina is days away from turning 16, and years ago, Parnassus lost her soul in a bet with Nick, who is finally coming to collect. But two things happen that could hold him back. First, both of them are gambling men, and Nick offers Parnassus a chance—the first to win five souls wins Valentina's soul. Second, the traveling misfits find a man hanging under a bridge. This is Tony, played by Ledger, an amnesiac scoundrel who also happens to be a terrifically good salesman, a trait lacked by the Parnassus team, and one that might just give them a chance at winning Valentina's soul.

But is Tony a good guy or a bad guy? Will he work for Parnassus or Nick? See, what's at issue is that Tony himself doesn't know that, just as he doesn't know who he is, how he came to be hanging under that bridge, or what, exactly, he did to deserve what's going on.

Like so many of Gilliam's films, the visuals in "Parnassus" are entirely unique and generally stunning, though not in the soulless CGI manner of so many Hollywood films. And the idea that when Tony enters into the Imaginarium he is transformed into someone else, either Depp, Farrell, or Law, is an interesting way of dealing with Ledger's death. But even though the ideas are appealing, what's lacking in "Parnassus" is a sense of fun. For an epic Gilliam tale of good versus evil, imagination versus the soul, and the final performance from Heath Ledger, the movie isn't terribly funny or joyful, something we've come to expect from the films of Terry Gilliam. Now, that said, Ledger is enjoyable to watch as he shills for souls, and Verne Troyer offers up hidden depths that no other director would ever give him the opportunity to explore. But it's almost tragic, then, that the film's most interesting character is Mr. Nick, played like a Satanic scenester by Tom Waits, who sizzles every time he's on screen. All three of those actors are doing something slightly different, as though they understand exactly what the movie was that Gilliam was trying to make—rather than the one that he actually did. Of course, we'll never know what this movie would have been had Ledger not died—or whether that would have been the film that Gilliam actually wanted to create.