Its very easy to hate this movie.

Rating: 9/10 (23 February 2015)

I will start by saying that this is not an easy movie to watch. Is not hard to understand why a lot of people think this movie is boring or it lacks of a good plot, you can find a lot of "simplistic" reasons to hate it (i.e. if you don't like jazz you will be annoyed during all the movie).
To understand what Iñarritu tried to express in this movie and to really enjoy it you need first to understand the inclemency and ungratefulness of the entertainment industry, new "superstars" are created every year while a whole bunch of "old not trendy stars" are left to the oblivion and eventually are forgotten (how many people you remember from the "in-memoriam" video every year at the Oscars?... how many "stars" you remember for their artistic achievements and not for their latest scandals? or they stereotyped characters: "the Rambo guy" the "terminator guy" the "superman guy" etc). In Birdman, Michael Keaton character was not recognized as a real artist until his emotional instability pushed him to the extreme where he had to shoot himself on stage and then only then, people "recognized" him as a true artist and not as the "birdman" guy. Before that scene people and media were more interested with him running naked on times square than his new artistic project. This happens all time in real life. Performing artists dedicate their entire life to achieve fame and recognition for their work but it seems they are only remembered by their mistakes or their personal life (who is dating who, who is getting a divorce, who naked pictures are leaked). If I ask you to repeat by memory the name of the last 4 Oscar winners for best male performance vs the name of any 4 "superstars" who have played a "superhero" character in the last 4 years I bet you will have an easier time answering the second one.
Birdman depicts a reality of our current society. If you change "birdman", for "batman" this movie is a partial biography of Keaton's journey through Hollywood.
If you watch this movie, without understanding the above, you will not enjoy it... Maybe is a movie made for people who have worked on the entertainment industry. I can assure you that old forgotten stars from the decade of the 70's 80's and 90's will feel very identified by a lot of lines and events in this movie.
Keaton character even "sacrificed" his personal life (daughter and wife) for a career that gave him a momentary and partial satisfaction, regardless of his artistic talents. This is a great movie that depicts the flaws and cultural emptiness of modern society.