The bizarre psychological dystopias of Philip K. Dick have, in recent years, provided ample fodder for Hollywood. Unfortunately, though, the usual treatment accorded to them involved dumbing them down, cutting out the thought-provoking elements that might annoy the average viewer who just came to see fights and explosions and stuff, "rationalising" the characters into a set that follow the Hollywood scripting rules, grafting in the usual action clichés, adding a romantic subplot so the action fans don't feel bad about bringing their girlfriends (extra revenue, you see), and hanging the whole garment on the shoulders of a larger-than-life star. Thankfully, though, Richard Linklater got to A Scanner Darkly before someone could make it into a Tom Cruise vehicle about a future dystopia run by evil psychiatrists or something, and he did a fine job with it, keeping it disorientingly true to the spirit of the book.
One of Linklater's previous films was Waking Life, a small art-house film consisting of people talking about the nature of dreams and consciousness. It was shot on video and then traced over by animators, resulting in a realistic yet stylised animation. Linklater ended up using the same effect for A Scanner Darkly, and it worked rather well. The story is darker, with its pervasive paranoia (some induced by highly addictive hallucinogenic drugs, and some by an intense war on drugs), and involves a government agent masquerading as a drug dealer (and user), who is then assigned to spy on himself (his supervisor doesn't know who he is, as all the agents wear "scramble suits" which disguise their appearances), and is soon wondering who exactly he is, and whether his confusion is a result of the institutional paranoia of the drug war or drug-induced psychosis.
The animation was of a higher quality than in Waking Life, which in some ways seemed like a rough sketch for this, and works rather well in the context of the film. Whilst some commentators doubt the point of animation that incorporates live-action detail rather than simplifying and caricaturing, it works rather well here (though one could argue that, much of the time, it isn't so much animation as a rather labour-intensive image-processing effect). The use of Thom Yorke's music in the closing credits was also an inspired move; Yorke's left-of-the-Guardian visions of a Blairite/corporatist hell aren't too far away from PKD's Orange County dystopias. And who would have guessed that it is possible for Keanu Reeves to not be annoying, at least when he's traced over by animators and furthermore placed in a scramble suit?