I heard the radio show (or rather the LP cast re-recording of the radio show) before I ever read the book.
I think it really does work best as a radio show. The books are fine but a lot of the delivery and weirdness is wrapped up in the original form, maybe?
I have a feeling it’s very hard to get hold of now. It’s also confused by there being audiobook versions of the books that I keep finding when I try to Google.