Thoughtful, character-driven...

Rating: 9/10 (10 February 2013)

First thing to get out of the way about "Looper"; time travel is a plot device, and nothing more. The movie is much more about the characters and the implications of their actions. It's kind of a philosophy treatise wrapped up in an engaging action plot.
There are multiple holes and inconsistencies in the plot. Honestly, they don't matter. This is a character-driven story, and a rather good one.
There's a neat, "noir-ish" tone to the movie. There's some exposition in the first half-hour that helps us understand the rules of this universe. A great many of these rules are explained in an early sequence where a friend of central character Joe (Joseph Gordon-Levitt) fails to "close his loop" by killing his future self. The results are gruesome, but not in any way we see explicitly.
Great sci-fi doesn't actually have to be believable. It just has to provide a setting for a story that wouldn't make sense in our own world. "Looper" turns out to be a very interesting contemplation of what makes people "good" and "bad" and does it with some smartly-conceived action and better-than-average writing.