After the trailer hit, there was always the sense with Birdman was probably going to be very, very impressive but perhaps a little too avant-garde for the Academy. A sort of Synecdoche, New York situation. That may still prove the case, though a slew of five-star reviews at the Venice Film Festival has done nothing to hurt its chances as Hollywood gears up for the long campaign to the Oscars.

Michael Keaton BirdmanMichael Keaton in 'Birdman'

Alejandro González Iñárritu's follows Michael Keaton - a former Batman, remember - playing an actor once known for portraying an iconic superhero. He struggles to mount a Broadway adaptation of Raymond Carver's What We Talk About When We Talk About Love and, in the days leading up to opening night, battles his ego and attempts to recover his family, career and himself. 

"There are streaks of 42nd Street, The Producers and Sunset Boulevard here, but otherwise, Birdman isn't much like anything else at all. Think Black Swan directed by Mel Brooks and you're in the vicinity, but only just," wrote Robbie Collin of the Telegraph.

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"Michael Keaton soars in this savagely funny, strangely sweet, sad and utterly brilliant New York-set comedy from Alejandro González Iñárritu," said Cath Clarke for Time Out.

Emma StoneEmma Stone in 'Birdman'

"Birdman" offers by far the most fascinating meta-deconstruction of an actor's ego since "Being John Malkovich," and one that leaves no room for vanity. From the moment Keaton first removes his wig to the sight of him wrapped in Batman-like facial bandages, his performance reveals itself in layers," said Peter Debruge of Variety.

"Birdman flies very, very high. Intense emotional currents and the jagged feelings of volatile actors are turned loose to raucous dramatic and darkly comedic effect in one of the most sustained examples of visually fluid tour de force cinema anyone's ever seen," said Todd McCarthy of Hollywood Reporter. 

Birdman - still considered a relative outside with the bookies to win Best Picture at the Oscars - hits theatres in the US on October 17, 2014 and in the UK on January 5, 2015.

Watch the 'Birdman' trailer: