The center of the movie is the word TRUTH

Rating: 9/10 (21 February 2015)

Summary: Truth=Birdman=Art=Superrealism=Truth
Pay attention to the scene where Mike says that everything on the set is fake, except the chicken: the chicken is a bird, so Birdman represents the truth. The truth, then, stands itself for art! Micheal, the main character, does not have any power: his inside voice, Birdman, tells him the truth every time. At the end, when he jumps from the hospital and his daughter sees him, he does not fly, but Sam joins the art too, because the art is represented by Super Realism, and nothing is more realistic than giving the life for a piece of art.
Micheal criticizes the criticizer because she labels everything, but she can't recognize art, she doesn't even know the name of a flower. So the entire movie is a rough critic to the actual cinema: people like action movie, such as superheroes movie (Birdman), but no one really cares about theater (seen by rich people who just think where going to eat later, who cannot judge something themselves, but who give too much importance to a review and to a single Name, Mike). Micheal represents the real art, which is not on Twitter, Facebook, Youtube etc. But despite he had the same art inside himself at the beginning of the movie, he becomes popular thanks to a ridiculous joke, when he walks half-naked in front of thousands of strangers. He does not belong the "social", as long as he chooses an old book to play on theater, but when you become famous, they know you, but they don't see you (Sam registered him on twitter, but everyone cares just about the half- naked video or the photo without nose). It is also a view of the actors life: if they are good in their job, they ruin everything in their real lives (see Mike), because they shift the reality to the show, leaving their lives, lovers and friends just with a hand of dust.
I've never seen something like this, for the music, for the techniques and for the depth of it. So I suggest you to watch it, being carefully to catch the real hidden meaning.