Just saw A Scanner Darkly, and I'm of mixed opinions.
On the one hand, director Richard Linklater delivers a suprisingly faithful adaptation of Phillip K Dick's story of near future drug dystopia. A cast including Keanu Reaves, Winona Ryder, Woody Harrelson and Robert Downey Jr deliver some excellent performances, and the film's unique rotoscoped visual style is unique and impressive.
On the other hand, though, Linklater appears to have no real feel for pacing or story continuity, and doesn't really achieve either a coherent science-fiction conspiracy story or Dick's mind-warping tale of drug abuse and its consequences.
The strongest parts of the film are the drug-warped Tarantino-esque conversations, and some of the very satisfying plot-twist reveals. The characters are well drawn and visually compelling. However, the film never really capitalises on any of these strengths, seeming almost scared of developing intensity and momentum. A very sedate and understated musical score contributes to a sense of aimlessness throughout the movie.
The film also ends on something of a turgid note. The transcendant monologues and images that conclude Phillip Dick's original book translate poorly to the screen under Linklater's authorship, and the movie finishes with a thoroughly butchered and near-incomprehensible text paraphrasing of the powerful author's note from the final pages of A Scanner Darkly.
As far as adaptations go, it unobjectionably translates the source material into a visual medium. But ultimately it adds nothing new to the work and suffers from a lack of real inspiration which means it's unlikely to convert new fans to Dick's writing.