PKD knew a thing or two about the costs of habitual drug taking, but do not expect this novel to take the form of a banal morality tale...there is far more merit to most of PKD's work.
The protagonist - Arctor/Fred is an undercover narcotics agent investigating the source of the enigmatic 'substance D'. PKD steers clear of what could be a predictable story line by having Fred (the agent) ordered to survey Arctor (the doper), this clever pretext allowing PKD to explorer the effects of the reality altering 'substance D', and paint his familiar plastic realities.
Arctor/Fred is typical of many of PKD's central characters in that he is a slightly flawed, and reluctant, everyman type. Possibly the Arctor/Fred character is slightly more one-dimensional than characters that PKD has used in other novels(Jack Bohlen (Martian Time-Slip) certainly seems more vulnerable, and Joe Chip (Ubik) is far more dynamic). One suspects that with Arctor/Fred, PKD is on such familiar ground.
PKD's writing style is typically efficient and unselfconscious, making this book like his work in general, misleadingly easy to understand.
Unusually for a 'Sci-fi' novel there is very little 'Sci-fi'. In fact were it not for the highly original 'scramble suits' which Fred wears to ensure his cover is never blown, and one or two communication devices, the novel could probably have been set in 1970's California. It is a shame that in doing this PKD might have gained more popular recognition as a 'serious' author, or failing that, have achieved similar sales to another tale of drug abuse - Irvine Welch's 'Trainspotting'.