Where the first book dealt largely with the question of humanity, the second deals a lot with the concept of immortality and what that transition would look like. It's absolutely stunningly a joy to read. Much like the first book, there's a kind of persistent optimism that persists all the way through. Even though so so much goes wrong, there's still a constant and consistent attempt to better the galaxy and the people around the Bobs. It's just a great thing to read.