The Discworld parts are still the best, especially the ones with the Librarian!
Like others, I am finding the book more interesting now that science parts relate to Earth rather than abstract ideas of space at large.
However, now that we are focusing on the make-up of Earth and life on it, I can't help but think that this book really is a mixed bag. Some chapters are great, some are ... not.
There is no need for some of the attitude - if the authors insist on calling things "lies to children" then by the same logic some of the theories the authors push must be "lies to children" also. Indeed, they seem to acknowledge this for some parts ... but not others.
For a book that is trying so hard to convince readers to look beyond the narrative and to question selective reporting, it still falls at the first hurdle ... even trying to sound objective.
Oh, and I skim-skipped through the parts about mathematical probability. In the words of (the best on-screen) Willoughby ... I will not torment myself!