It's a collection of columns that Hofstadter wrote for Scientific American. It explores a lot of topics, but personally the one I found most interesting was "superrationality:" https://en.wikipedia.org/wiki/Superrationality

it's absolutely the book of his I but copies of to give away. GEB was impressive in it's own way, but a bit too self-indulgent to be fully engaging, and 'le ton beau de marot' is spectacular but pretty narrowly focused. metamagical themas is just plain great in every respect.