Reviews mixed for Heath Ledger's final film

Heath Ledger's final film has met with a mixed response from movie critics ahead of its premiere later this month.

The Imaginarium Of Dr Parnassus — starring Christopher Plummer as Doctor Parnassus and Ledger as the doctor's young helper Tony — is a fantasy film from British director Terry Gilliam that follows a theatre troupe engaging in a magical journey.

Ledger was midway through filming the movie when he died from a prescription drug overdose in a New York apartment on January 22 last year.

Instead of canning the production, Gilliam instead cast three other actors #&151; Johnny Depp, Colin Farrell and Jude Law — to play Ledger's character in the remaining scenes.

An incredible amount of hype has surrounded the movie since Ledger's untimely death and while critics have generally praised Ledger's performance early reviews of the film have been mixed.

James Christopher, reviewer for UK newspaper The Times, said a weak storyline failed to support Gilliam's "mind-bending illusions".

"The story that holds these visions together is slim, incomprehensible, and desperately unconvincing," Christopher wrote, giving the film two stars out of five.

He did heap praise on Ledger, saying his performance was "a marvel to watch."

British film magazine Empire gave the film three stars out of five, with reviewer Olly Richards saying director Gilliam is "the real star".

"Parnassus isn't a total success — a storm of imagination turns into a bit of a disappointing drizzle at the end — but it's a directing achievement to be applauded," Richards wrote.

The film opens in the UK on October 16, while Australian audiences will have to wait till October 29.