I can say BOYHOOD doesn't have a gimmick -- it has a remarkable style of filmmaking whereby, for the first and only time in film history, a group of characters is followed over a period of years that corresponds to the number of years the film took to produce, you get to see the actors age in their roles as their characters age in their onscreen lives. A remarkable, unprecedented accomplishment, absolutely essential to the film's impact, a transcendence of all the usual tropes of multi-year storytelling: different actors taking on the same role as years supposedly pass, latex aging makeup, and so on.
BIRDMAN, on the other hand, is one cheap filmmaking gimmick after another, the long long long takes blatantly stitched together to make an illusion of seamlessness, a bunch of Big Scenes For Actors that never coalesces into anything of interest or importance at all, a whole cheesy BLACK-SWANesque level of Is It Real Or Is He CRAZY bullsh*t. BIRDMAN is a void wrapped in an emptiness shrouded in an absence tied up in a bow of technical showboating designed to disguise how utterly useless a filmmaking and filmgoing experience it really is. Gimmickry at its purest.
"If they can get you asking the wrong questions, they don't have to worry about the answers." Thomas Pynchon, GRAVITY'S RAINBOW
"Reality is that which, when you stop believing in it, doesn't go away." Philip K. Dick
My blog: http://www.roscoewrites.blogspot.com/