All in all, this is one of the better film adaptations of Dick's work, although probably for aficionados only; the uninitiated would almost certainly be confused and exasperated.
It follows the novel closely, and the rotoscoping is effective and unsettling, especially when depicting Arctor's 'scramble suit'. But the animation is, oddly, let down by the acting; Rory Cochrane is over-the-top as Freck, and Barris, whilst suitably sinister, is often unintelligible thanks to Downey's rapid, mumbled delivery. Keanu Reeves puts in a solid, tortured performance, and we warm to Winona Ryder's Donna as the film progresses.
But somehow the film fails to successfully capture Arctor's growing paranoia and his tenuous hold on reality, or the hopelessness felt by all the characters as they wander, drug-addled, though a surreal Californian suburban landscape.
Dick has not been well served by Hollywood. Even Blade Runner only scratched the surface of the complex novel on which it was based, and others, like Total Recall or Paycheck, come nowhere close. Minority Report was surprisingly faithful to Dick's short story, although lost several brownie points for (a) starring Tom Cruise; and (b) a predictable dose of Spielberg sentimentality at the end.
One day, maybe, someone will make a film of a PKD novel which actually works, one which captures the freewheeling weirdness of his plots, without losing their humour and essential metaphysical content - Ubik, possibly, or even Palmer Eldritch. But I'm not holding my breath.