I just received my PRS-600 in the mail today, so I can't give you too much information on pdfs, but at the moment I am very pleased with how it displays them. For an ebook reader, I found the kindle dx to be a bit large and lacking in features. Just so you know where I'm coming from, I read mostly technical books/journals in pdf format. I gave your book a shot (sorry, my camera is horrible) and it is very readable in landscape and portrait mode. So far, I personally prefer reading in landscape mode, which basically shows you half of the page at a time.
One recommendation would be to crop books like the one you posted. There is no reason to lose screen real estate because of a giant margin. In a program like acrobat, it only takes a few seconds to do and can make a big improvement.