Now, don't get me wrong -- the temporal gimmick that sends Memento careening from reel to reel is a humdinger, and I offer major props to screenwriter/director Christopher Nolan (working from a short story by his brother Jonathan Nolan) just for making it cohere so fiendishly well. Few movies force so much brainwork; for a good chunk of its running time Memento makes you feel like you're scrambling just to keep up -- and, more, that you enjoy the scrambling -- and that's an immensely pleasurable sensation for a moviegoer.

I'm going to spill a few beans here, though it's not my intention to spoil the film; if you've not seen Memento, you may not want to read one sentence further. Because Memento is a story told in reverse, and I can't for the life of me think of a way to verbalize my complaints about the way it unfolds without reference to this fact. The ingenious concept works because protagonist Leonard Shelby (Guy Pearce) suffers from short-term memory loss; talk to him for more than a few minutes, and he'll forget how the conversation started. Leave him alone while you use the bathroom, and he may not remember who you are when you return to the table.

Leonard remembers everything that happened in his life up to and including one crucial, world-changing event -- the brutal assault that claimed his beloved wife and left him brain-damaged. On a quest for revenge, Leonard has taken to tattooing his body with crucial bits of information. The words that arc beneath his collar read, when viewed in a mirror, "John G. raped and murdered my wife." Leonard's effort to trace the elusive John G., by leaving himself notes scribbled on Polaroid photos of quickly forgotten acquaintances and by inking hard information on the criminal into the fabric of his body, is as compelling as cinematic crises come.

Over the course of Memento's running time, however, I grew removed from the proceedings and the film eventually lost me. Part of the problem is that the story is moving on an inexorable trajectory toward a fixed event; it gets its charge by giving viewers an emotional stake in the race back to that point in time. But at a certain point, it becomes clear that events are transpiring at far too leisurely a pace to get us all the way there. Instead, the narrative relies on a great deal of elision and some lengthy exposition in order to fill in what's revealed to be a typically convoluted backstory. Breaking the golden rule of storytelling, Memento tells us, rather than showing us.

The ultimate effect is actually more literary than cinematic -- instead of exploring Leonard's affliction using the grammar of film, Memento pulls the perceptual rug out from under us by challenging Leonard's internal ideas about his own personal history. (I found myself thinking of Jonathan Lethem's novel Motherless Brooklyn, whose protagonist suffers from Tourette's Syndrome and thus brings a unique perspective to his verbal world; I don't think Memento has any similar perspective on its own cinematic world.)

By saying Memento is not particularly cinematic, I mean partly that it's not especially interesting to look at, and that visual ideas are incidental to its real ambitions. As a conventional narrative, it's pretty flat; although the performances are uniformly fine, there's no denying that the troubled-loner-meets-femme-fatale scenario has grown banal through overuse, and Leonard's existential plight barely has a chance to click before the ever-more-complicated narrative threads start to undermine our sympathy for him. (If everything that happened on-screen was as graceful, fascinating and heartbreaking as, say, Exotica -- just to name another exquisite puzzle-box of a movie -- it would be a different story.) The performances are generally fine, although Pearce may be just too stoic as the noirish central figure.

Also I think Memento suffers when compared to a truly avant garde film that deals in similar themes, such as Marienbad. Resnais really makes something out of subjectivity in that film, telling multiple, contradictory stories in the first person. Memento's point of view, by contrast, is relentlessly objective. And where traditional film noir specializes in making audiences share the doomed hero's very subjective feeling of being caught in a cold, dark place, Memento ends up giving them the very cool pleasure of being omniscient third persons to whom secrets unknowable to the protagonist are revealed. The opening sequence, which is played completely in reverse, only further abstracts our relationship to the character we're watching.

So Memento's flaw, I think, is one of disconnection with its own internal life. The inverted narrative coheres, but it also severs the relationship between audience and protagonist. At the end of the film, you're the holder of privileged information that makes you smarter than Leonard and leaves him stranded in an increasingly complicated loneliness. Crucially, you haven't experienced the world in the same way that Leonard experiences it, which means that you haven't shared his journey. Rather, you have been taken for a ride by an immensely clever filmmaker. Sometimes, I guess, that's enough -- as long as you shuffle off the feeling of emptiness that follows the trip.