My very-informative reaction to The World Without Us: ehh. My apologies to Juniper Pearl if she's still coming around here, but I feel the same way about this book as I did with Malcolm Gladwell's Blink - a decent magazine article has been overstretched to book length.
I've always thought it would be kind of cool to watch nature reconquer our civilized spaces, and there's a fun animation showing this at the book's website, but after a while the fascination with the idea fades away. And the book uses that idea mostly to show how badly we've screwed up the planet, which I guess is okay but depressing.
The book isn't bad. The part about the Korean Demilitarized Zone was interesting, as well as the potential danger from microparticles of plastic to ocean life. I think he's got a bit of a Jared Diamond problem though of covering too many subject areas to be completely accurate, without Diamond's high ratio of interesting ideas that makes up for occasional errors.
Worth skimming, I think, but I can't tell people to rush out to get it.