PKD is one of my favorite sci-fi writers and I recommend Ubik if you're a new reader, although like the article mentions, you definitely need to be in a certain mindset to "get it." The Man in the High Castle has an interesting concept but I don't think it's particularly well-written. One thing that I think goes unnoticed about PKD is how some of his earlier short stories are undeniably, unquestionably bad. Fair Game…
Regarding Ubik, there is a Russian movie, Koma, that looks like it had Ubik as inspiration, and in that probably is more faithful than most Hollywood adaptations of his work.