Spectacular, star-powered cinema that makes us ask anew what cinema is for. Call it a "Dark Knight" of the soul.

Birdman is a rich, startlingly clever and multi-layered collage, with Iñárritu creating a meta-universe of mirrors and performances upon performances.

The film's exhilarating originality, black comedy and tone that is at once empathetic and acidic will surely strike a strong chord with audiences looking for something fresh that will take them somewhere they haven't been before.

It’s borderline miraculous.

It's dazzling and rambling, intimate and sprawling, and it's carried along by an infectious, off-the-cuff jazz score. As soon as it ends, you'll be dying to fly with it again.

A triumph on every creative level, from casting to execution.

Birdman dares to be ambiguous, but unlike most essays in ambiguity, it is also a hell of a lot of fun.

Moment to moment, Birdman manages to shift gears, its roaming camera revealing new surprises as it glides along. That degree of unpredictability provides it with the ultimate response to the sea of formulaic mediocrities at the center of its critique.

The director has wisely assembled an ensemble of performers who know how to handle a long take; this will certainly rank among Keaton's career highlights — in a role that allows him to completely dump out his paintbox and show a vast range of emotion — but everyone shines.

There’s no doubt it makes for a jubilant ride, a galvanic first blast. But it remains a film which feels deeply thought rather than deeply felt; a brilliant technical exercise as opposed to a flesh-and-blood story.