It has everything to entertain and challenge.

Rating: Null/10 (30 October 2014)

"Popularity is the slutty little cousin of prestige." Mike (Edward Norton)
Birdman or (The Unexpected Virtue of Ignorance) is important to see if only for Michael Keaton in the titular role, a has-been movie hero (Birdman) hoping to make a comeback as director, writer, and actor in his Broadway adaptation of a Raymond Carver short story. Keaton will be nominated for an Oscar; he's that good.
The film is also a witty commentary on celebrity (as the above quote attests), its tragic consequences when success does not follow success. In addition, collegial relationships are explored during the high-strung rehearsal of gifted actors at the St. James Theater on Broadway, challenging each other in professional and personal ways.
No fellow actor is tougher or brighter than Edward Norton as Mike, whose thespian gifts are generously displayed but who is sexually impotent off stage. When he works on stage with Keaton and Naomi Watts, the acting is better ensemble work than in any other film I can think of this year.
Besides the stunning acting, the camera and editing are to be experienced: the careering camera visits dressing rooms, hallways, and stage without skipping a beat--the director is extending takes and cutting minimally, letting the camera do the work while scenes follow scenes seamlessly. The effect is the high-energy of creative people bursting the confines of narrow backstage to emerge in the seemingly endless space of the stage, an expanse waiting for the egos and talents to fill it.
It's all about acting, and it is not always pretty:
"I wish I had more self-respect." Lesley (Naomi Watts) "You're an actress." Laura (Andrea Riseborough)
However, it's Keaton's acting that dominates: edgy and impatient, on the lookout for the right nuance, diffident and dreaming--he's an artistic mess. Along with some gritty realism comes a modicum of magic realism such as telekinesis and flying, both not so weird given the creative energy that seems to come out of the walls.