GEB is nominally a book about a mathematician, an artist, and a musician but as the author writes in the 20-year anniversary edition, "In a word GEB is a very personal attempt to say how it is that animate beings can come out of inanimate matter." Or to the point, "I have tried to weave an Eternal Golden Braid out of these three strands: Godel, Escher, Bach."
The book is structured in an unusual way: as counterpoint between Dialogues and Chapters. Math is hard enough but this structure tends to lessen the burden. I'm resigned to not fully understanding the math in my first reading. The book is essentially about "Strange Loops" with perhaps the most pressing today being can intelligent behavior be programmed? The author puts forth that this seeming contradiction is no contradiction at all. I guess we'll see.
The book has been called the bible of artificial intelligence since it first came out who's to argue.