Several people have said above that the trilogy changed them, and that is certainly true of me also. I don’t think you can say that about many books.
Regardless of whether it changes you, it certainly had a lasting effect on the culture in general, especially the sf-fantasy-computer-geek-RPG world that’s edging closer to the mainstream as we speak. The concept of “ha ha only serious” and the humorous take on Dada Zen are both deeply entwined in that book, Groucho Marx, and Bugs Bunny. The Church of the SubGenius (with Ivan Stang, ex-nabob of “High Weirdness by Mail”, and J.R. “Bob” Dobbs, Salesman to the Saved) is a slightly more modern offshoot of Discordianism, and is more obviously a parody of the moronic End-Times flavor of Apocalyptic Protestantism.