I sorta buzzed through this book without sitting at my computer running the code as I went, which is almost certainly not recommended practice. I'm sure I'd get more out of it if I'd "done it right". But here we are.
Anyway, this is a fun enough little book, and does a good job of showing how much you can accomplish in R without many lines of code. Real world case studies, as used, are definitely a good thing for a book like this, even if changing APIs bite them in the butt occasionally. I was already reasonably familiar with R and many of the techniques for machine learning they discussed, so I can't say how good the book is for learning those things from scratch or so. I hadn't heard of (or, at least, don't remember hearing about) "Multidimensional Scaling" (MDS), for looking at clusters, so that was a fun little learning chapter.
Honestly, I probably enjoyed reading Programming Collective Intelligence more than this book, but that may have been because most of the material was new for me for that book, and it used Python.
I know writing books is hard and all, but there were enough typos (in text, code, and even a link), and at least one mis-referenced figure, that I sort of had the feeling this book might have been rushed out the door. And I know the book was purposefully not being too detailed mathematically, but the little description of the Konigsberg problem ruffled my feathers. It's Euler, it's worth doing it justice.
This book didn't have a very contiguous feel, to me. Maybe that's the result of having two authors, I don't know (at some point I figured you could take writing samples from the author and train a model to predict who wrote which chapter). One chapter dealt with dates one way, and then another chapter used the lubridate package. In the chapter just after the built-in dist function was used, a hand-rolled version was written. The depth of coverage of some of the math also seemed inconsistent, like some things were easy so we'll spend a page or more on them, and some things aren't as easy, so don't warrant any description at all. Probably better, in my mind, would have been little clearly-denoted "skippable" mathy sections. Finally, the graphs regularly employed colors, which were generally indistinguishable in the print version - I guess if I'd been running the code as I went, it wouldn't matter.
Anyway, enough criticism. It's a fun book with good examples and it demonstrates the power of R