I would argue that “changing the way you think” doesn’t require the book to be factually accurate. The idea that external factors like geographical starting conditions can have a huge impact and shape things as complex as human culture is a powerful one, regardless of the conclusions drawn in the book.
If anything, the way it has been challenged and shown to be flawed is a lesson on and of itself - that complex systems have emergent properties, and that those starting conditions are not as deterministic as it might appear at first blush.
If GG&S changed the way you think, I'd highly recommend following it up with either the book from that review (Eric Wolf's "Europe and the People without History") or Ian Morris's "Why The West Rules, For Now".
Guns, Germs and Steel is an absolute garbage book. It's pseudoscience, plain and simple. It's teaching unacceptable ways to think about culture, by any anthropologist's standards.
If anything, the way it has been challenged and shown to be flawed is a lesson on and of itself - that complex systems have emergent properties, and that those starting conditions are not as deterministic as it might appear at first blush.