You notice very early that this isn't your typical "Hollywood" film. Birdman takes chances and I admire brave filmmaking. Overall, it is very worthy of all the awards and accolades it received.
The only complaint I have is that I didn't particularly care for the ending. The last 15 minutes or so go too far "out there", but not enough to take away from the value of the film as a whole.
Recommend. Especially if you were introduced to the Batman universe via Keaton and Burton.