Done? Ok… The main surprise for me was how many seemingly unrelated topics the book touches. Logic (Gödel), graphic art (Escher), music (Bach) to start with. But also mathematics, molecular biology, genetics, philosophy, zen buddhism, formal systems, artificial intelligence, programming, recursion and self-reference, various paradoxes, and much much more.
It is easily the best book I’ve ever read, although I can’t claim to have understood everything. If you want to borrow my copy, I’d be glad to help (the book is sort of expensive and really hard to get in Czechia).