The "disappointment", if that's fair to say, of Looper is that unlike the last collaboration between writer/director Rian Johnson and actor Joseph Gordon-Levitt, Brick, it doesn't do anything to seriously up-end or redefine its genre. What it must settle for, then, is to be an extremely good exemplar of its genre, at which point the word "disappointment" really must be left far behind, because we're not trying to be assholes over here, or something.

Particularly since the genre in question is the time-travel movie, a particular sub-set of science fiction that, when it works, can be deliriously good (I point you to the immaculate screenplay for Back to the Future as proof). Looper cheats a little by using time-travel as an anchor for its concept, rather than as a mechanic driving the plot; it cheats even further by setting the "present" in 2042, and all of the time-travelling comes backwards to that point from 2074, even though most of the movie looks like the 1990s. And thus the film is dislocated such that we're not immediately going to hunt for the breaks in the concept (of which I did not see any that couldn't be readily swept away with a little fan-wanking), because there's no "normal" in the film to begin with.

Anyway, the hook - which gets explained in slightly too much voice-over telling and not enough complex mise en scène showing, but since the voice-over is courtesy of Gordon-Levitt in full-on "weary detective" mode, it goes over well - is that by 2074, time travel has been invented; and it is only used by criminal organisations sending undesirables back to 2044, when time travel has not been invented, to be assassinated far from the probing forensic science of the 2070s. In 2044, the hitmen thus hired by the mob's gone-back-in-time-and-become-a-ganglord Abe (Jeff Daniels) are called "loopers", one of several jargon words briefly explained for us; the name comes from the "loop" that gets closed when a hitman is no longer required, and is obliged to kill their 30-years-older self, upon which they are given a golden parachute theoretically sufficient to last until the time when they are captured by the mob and shipped back to commit the strangest form of suicide yet devised. "Loopers don't have the most foresight", narrates a giddly dry Gordon-Levitt, or words to that effect (I apologise for not taking notes).

It's easy to get bogged down in the elegant complexity of the looping scenario (the film gets its share of comparisons to Inception, though the only use I see in doing so is to point out that Johnson, compared to Christopher Nolan, is not nearly so anxious to explain his difficult concept over and over until we have it drilled into our head, and thus is Looper a considerably fleeter, cleaner screenplay), so let's cut to the literal chase: "our" looper is a guy named Joe (JGL), who like all of his colleagues is addicted to narcotic eye drops (because It Is The Future!), who has noticed with only minimal alarm that loops are being closed at an unusual rate lately, until the time comes for Now Joe to come face to face with Future Joe (Bruce Willis), and put a bullet in his head; but Future Joe has other plans, and manages to escape, after clocking himself in the head and knocking himself out. As it were.

Basically, there's a crimelord, the Rainmaker, in 2074 making everything extraordinarily bad, and Future Joe wants to take him or her out in 2044, as a 9-year-old. Present Joe wants to kill Future Joe to avoid being killed by Abe's team of special thugs, the "Gat Men", primarily the singularly efficient and deranged Kid Blue (Noah Segan); he also meets up with and falls for the mother of one of the three potential Rainmakers, Sara (Emily Blunt), meaning that he wants to kill Future Joe before he can kill the kid (not knowing which is which, he's hunting all three - and if there's one thing I did not expect to see in a movie, ever, it would be Bruce Willis sobbing after murdering a 9-year-old boy). This all takes place in a tech-noir version of goddamn Kansas, which I find indefensibly delightful.

The one thing I really expected the film to be, a tense psychological game between the younger and older versions of the same man, is something it's definitely not. But to its credit, it manages to be a whole host of other things: chief among them, a crackerjack thriller that moves like a cheetah when it should, and slows down at just the right point for one of those quiet country idylls that used to be an important part of these chase-type movies, but haven't shown up so often. It has a few (blissfully few) big effects scenes, several well-done shoot-outs, and an attention to character that is inordinately gratifying in a contemporary sci-fi movie: Johnson and his actors take time to make certain that we actually care about the people in the movie, rather than simply observe them being driven like cogs.

On the level of sheer genre storytelling, Looper is, I find, extremely satisfying; that there is no such thing as a time travel movie that is universally satisfying, we will take as read. Anyway, Johnson doesn't get bogged down in twisty causality and predetermination games, as will happen (it is, for example, the primary motivation behind the gloriously low-tech Primer); his idea of time travel is significantly more plastic than in, say, 12 Monkeys, just to keep it in the Bruce Willis family. So, for example, we have the excitingly unique idea that Future Joe doesn't keep his memories intact, since by showing up in the past and altering things, he is causing his memories to flicker in and out of existence.

Is this, and other places where the film defiantly refuses to lay out an exhaustively intertwined series of causes and effects, just Johnson's way of saying, "go with it, have fun with the chase, and don't sweat the small stuff"? I think it is (particularly since a piece of narrative says much the same thing), and given that Looper has the goods as an action thriller, going with it is easy to do.

It's easy to complain about the roads not taken: the scenes between the two Joes (Gordon-Levitt wearing make-up that makes him look not especially like Willis, though not like himself, either, and at the very least, it doesn't look fake) are so good, well-acted with sharp dialogue and relatively hefty ideas, that it's a crying shame there aren't more of them; there seems like there could have been more time-jumping tricks like the way that messages are carved in hapless 2042 loopers to leave scar tissue messages to their future selves; and the whole Kid Blue plotline doesn't pay off nearly well enough to justify the time spent on it. It would have been easier for the film to be much, much smarter than it is, though at least it doesn't put on airs - it is designed to be difficult up to a specific point, and there it cuts off.

But for all that, the movie is the best kind of light entertainment that expects you to be just as intelligent as it is, and its sense of dry sarcasm (the whole of Gordon-Levitt's performance, most of the laugh lines, making 2042 Kansas look so much like Kansas at any point in the last 30 years) makes it fun to watch even when it's indulging in overblown violence (one slow-motion blood explosion is a strong contender for Most Poetic Messy Death of 2012). And that so much energy could be spent in creating a world of loopers and eyedrop drugs and alternate universe side-flashes to China and a weird collision of future tech with outmoded guns, and that this world is then used chiefly as an excuse for watching how some well-written, well-played characters interact with it: that is something I have to respect. Plenty of filmmakers pay lip service to human behavior while grinding through their hopped-up concepty scenarios; doing it the other way around is, at least, proof that Johnson continues to have his priorities firmly in the right place.