Don't freak out if you can't get past Joseph Gordon-Levitt's face prosthetics. I don't think you're meant to.
Taking a good-looking movie star mug and altering it in the name of disguise -- Charlize Theron's teeth, Nicole Kidman's nose -- is about abandoning the actor's larger-than-life, off-screen identity, it's about forgetting. Taking a good-looking movie star mug and delivering it to a head-scratching, discomforting, "uncanny valley," a location where nobody looking at the screen can ever shake the sensation that they're staring directly into something wrong? That's about not forgetting. And when asking the audience to accept another actor popping up in the same role as the plot moves back and forth in time? That's intentional disorientation, a filmmaker never letting the audience stand on solid ground. And that is awesome.
Gordon-Levitt plays a "looper," a hired assassin who time-travels to make his hits. He has the face of a person who may, with your helpful imagination, grow into Bruce Willis thirty years from now. G-L plans to cash out, "close the loop" by killing his future self, then spend the next 30 years enjoying Paris. Willis, however, has other, equally self-serving plans, and the two sides of this single human coin spend the rest of the movie in a kind of Spy vs. Spy carousel-chase in order to protect their own futures and to wrestle that far-off day from something horrible called "The Rainmaker." Emily Blunt, as a lady-farmer with an estranged child who won't call her "Mom," is involved in this. So is Piper Perabo, as a stripper with a heart of money. So is Jeff Daniels, the kill-you-now boss who wants everybody to play his way. And most importantly, so is director Rian Johnson, who's trying to simultaneously melt your mind and your heart with a multi-level maze of a plot that would take my entire word count and a couple of dry-erase charts to map out.
By this point in movie history, the time travel tease has been dissected and exploded and mangled into shapelessness. To tell a story that requires its characters to erase one gesture, either now, then or in the way-back, means that all other gestures are compromised. The story collapses. Nothing works. You might walk out of the theater happy but that nagging nerd inside is complaining, "But what about...?"
Which is why, in this puzzle-play, time travel is a trippy component, but not the hill it wants to die on. On a visceral level the emphasis is, obviously, the tornado of sensation that comes standard with characters who pop back and forth between decades, a fast-paced blast into the impossible, delivered with an emerging laundry list of stylistic influences first presented in Johnson's staggeringly cool teen-noir Brick (at one point Daniels tells Gordon-Levitt, half-scolding, "The movies you're dressing like are just copying other movies.")
But where it counts in the long-term, in the movie-loving, grab-your-heart, rewatch-this-thing side of your brain, the point is salvation. It's dressed up in angry-future sci-fi clothes and carries giant, wonky, anachronistic blunderbusses that miss as often as they hit, but that's just a cloud of coolness to keep nakedly emotional ideas about sacrifice, love, self-preservation and the longing for a better world from overpowering the action. It strikes a tightrope balance between intimacy and gun-blasty bombast that you won't forget. And in the end the meaning is clear as a bell, even if you can't always figure out how it got you there.