Art? What art?

Rating: 1/10 (18 March 2015)

I watched this film knowing nothing about its content, about other people's opinions nor reviews. I wanted to watch it just because I saw in the past some films by its director, films that I still enjoy like "21 grams", "biutiful" or "amores perros".
This "Birdman" was a huge disappointment. Very early in the film you'll understand that the whole picture consists of one (supposedly one) single single (which seems to be not true, as there are come cuts there), something not new, as Alexander Sokurov made the same with his "Russian Ark" in 2010 (although the Russian film seems to be truly one single shot film, with no CGI. And that's it.
Michael Keaton's performance is - in my opinion - above average, and there are some quite nice compositions here and there, but a film can NOT be just that. The plot is too simple, the soundtrack is annoying and the intrigue is not there at all. I see no "art" nor "artsy" substance in this film. I read some reviews where some people praise/mock its "artsy" approach, but besides some very few details the film follows the cliché pattern of most films present in the Oscars annual competition.
So my question stays: Art? What art? The annoying soundtrack for two hours on the back of a 2 hours apparent single shot?