Sorry, had to get that off my chest. The link's work-safe, though obscene.
Someone asked me why I cared so much and found him so abyssmal a casting job just now. I explained it thus:
imagine Keanu Reeves as Harrison Ford's character in Bladerunner: that's the role they're casting him in. However, A Scanner Darkly is a much more human story than Bladerunner's basic theme of 'what /makes/ a person human?', so imagine Keanu Reeves playing a Ray Deckert who has to very personally CARE about the people he's investigating- and get driven a bit batty by the extreme dichotomy between his work life and his personal life.