Actor Joaquin Phoenix's new movie I'm Still Here, which documents his attempt to launch a rap career, has been panned by critics.

The movie, directed by Casey Affleck, premiered at the Venice Film Festival earlier this week.

Phoenix was followed by cameras over a twelve month period for the fly-on-the-wall documentary, which has divided cinema-goers over whether or not it is a hoax.

Robert Ebert, film critic for the Chicago Sun-Times, said the movie shows how Phoenix “has lost contact with his inner self”.

Slate critics Dana Stevens wrote: "The worst thing about 'I'm Still Here' is the fact that it exists."

But Entertainment Weekly critic Owen Gleiberman was more positive, writing that I'm Still Here is “a riveting — and, in its way, cautionary — case study of a celebrity self-destructively addicted to his own psychodrama”.

I'm Still Here is released in the UK on September 17.

(by Jason Gregory)