Now we know:
Dick recognized that it was not at all science fiction as he and his cohort were used to, but something new, different, and in many ways better.
With all due respect to Dick, I cannot help but agree. The book is quite good, but the movie is great. While the book has many great ideas, the movie immerses the viewer in a whole new dimension and opened up new realms of possibility for science fiction writers. This is a rare case in which the film is better than the book, and we are all happier for it.