I think the title is somewhat misleading, it wasn't just good old Genghis who changed the world, but his sons and grandsons. And change it they did, without a doubt. Did they change it as much as stated in this book? I don't know. I also don't know enough to put forth an intelligent argument for or against.
What I do think is this should have been written as two books, Volume I on Genghis (who dies fairly early in this book) and Volume II on the rest of the crowd. I have read a few books on Genghis, and while this book does bring to light some heretofore-unknown tidbits, it doesn't tell nearly as much as I'd hoped, especially from Weatherford. I've also read a couple of books about Kublai, and again, this book seemed to gloss over some fascinating areas. Two books, each in the 400-500 page range would have been a treat most rare.
I won't get into the "who invented noodles first" – Mongols or Europeans argument? From what I've read just about all agricultural communities that grew wheat or a similar grain, came up with a form of noodles. And also, from what I've read, the Mongols had a real antipathy toward blood and raw meat, and I can't help but wonder about them placing meat between them and their horses to tenderize it. Between the horse and the saddle would seem to be a. unbalancing, and b. too iffy to rub sores on the horse. I believe they did put milk in bags tied to their saddles to beat it into butter or yogurt, or at least fermenting it. I can picture them doing the same with the meat to tenderize it, but cooking it later.
I absolutely loved the parts where Weatherford talked about having been there, seeing the places, being with the locals who explained various things to him, such as why horses would go in this direction, how to tell if the ice is thick enough to ride across, etc. I also appreciated the maps. Really appreciated the maps!
All in all, if you're interested in Genghis Khan, read this book. But don't stop when you put the book down. Try some of John Man's books; he, too, has been there. This book is easily read, it is not a textbook, it is very accessible to the average person, and the history buff will, I'm sure, enjoy it. I did. There are several excellent books out there about Genghis, and this is a good one.