Very nice - after looking through the free PDF for 15 minutes, I ordered a print book to encourage and support the author. (I have done the same thing using Lulu: I get 200+ free PDF downloads a day for my Java AI book, and it is a good feeling when people occasionally order the print book).
I've actually been reading this book over the past few months. I just stumbled across it while looking for info on neural networks in Ruby. The book takes a very clinical approach, but the code samples are surprisingly accessible.
I haven't bought the book yet (I read it on my iPad), but I will eventually buy it if I can't find a decent digital download. For some reason I'm so much more inclined to buy books offered for free than not.