Birdman is a glorious run-on sentence of a film, a bizarre but welcome transformation in the career of cowriter/director Alejandro Iñárritu, and the platform for maybe three career-best performances. It's also a frustrating work of art that repeats itself mercilessly, falls in love with its own gimmickry, and seems to be unsure of what it's trying to communicate to its viewers. It contains multitudes, contradicts itself, and apologizes for absolutely nothing.
Birdman stars former cinematic Batman Michael Keaton as Riggan Thompson, an actor who reached the peak of his popularity with a series of 1990s superhero films. Riggan is trying to write, direct, produce, and star in a Broadway adaptation of Raymond Carver's story "What We Talk About When We Talk About Love," but the production doesn't gel until a gifted younger actor named Mike (Edward Norton) joins the cast and starts remaking the play in his own egomaniacal image. Meanwhile, Riggan's daughter Sam (Emma Stone) is fresh out of rehab; she's full of rage, and she's desperately trying to figure out where she should aim it.
So you've got a film about the making of a play starring one actor winking at the superhero-ification of Hollywood that he helped pioneer, another actor playing up his own past history of on-set difficulties and artistic pretensions, and a third mimicking an all-too-common real-life starlet trajectory. It's so postmodern, it's practically gone back around to straightforward again. When you slather on the many constraints and ambitions, it sounds like a film made up entirely of concept. Most notably, Birdman looks as though it's made up of one long tracking shot, even though the narrative takes place over a couple weeks. Antonio Sanchez's magnificent score is largely percussion based, meaning many of those tracking shots consist of actors running around to jazzy drum solos. Surrealistic visual touches invade the narrative in the form of blockbuster special effects crammed into Riggan's claustrophobic world.
Remarkably, most of these decisions don't overwhelm the narrative. Instead, they inform Keaton's brilliant performance as a self-obsessed schlub advocating desperately for his own relevance. All these bold choices blend together in an astonishing act of collaboration—you can't believe the movie works, even as it unfolds in front of you.
Not every decision is for the best. Zach Galifianakis, as Riggan's friend and lawyer, is seriously outclassed as a performer. Cast alongside subtle performers like Naomi Watts and Amy Ryan, Galifianakis telegraphs the slightly panicked air of a sitcom star on a live televised broadcast; he flubs lines, goes weirdly broad a few times, and generally behaves like he's in a different film. And though repeated viewings may convince me otherwise, I'm not entirely sure Iñárritu knew where to end the film, as though he became tangled in all the postmodern threads as he struggled to find an original conclusion.
If you like overambitious, overstuffed entertainments by world-class artists—think Jonathan Lethem's Chronic City, Haruki Murakami's Wind-Up Bird Chronicle, and Brian Wilson's Smile—you'll find a movie to lose days on, pulling apart and investigating every stylistic flourish or actorly tic. But after you've engaged in that kind of an intensive conversation with the film, there's a good chance that you might find yourself with nothing more than a lap full of colorful confetti. And the thing is, that might actually be Iñárritu's intent with Birdman; there's probably a very good reason why the two most meaningful sentiments in the whole film are written on tissue paper. 
