Read it. Didn't think much of it. Goes by the idea that most of human achievement is an accident of location. The thinking of the book is very linear. A+B=C. Nothing else can get in the way. If some point of human history does not fit the theory, it gets discarded.
Not an easy read either. Not enjoyable. I equate it to the idea that, "if you suffer for something, it must be worth it". Sadly, this is rarely the truth. "Guns, Germs and Steel" is overated. There is some good stuff in it, decent theories. But he does not do a good job when he sums it up. His attempt at "the grand theory of everything" fails.