This is an excellent product. As I have seen commented in other reviews, the Spine (Chapter 1) alone is worth the price of the PDF. The notes, rules, and ideas the authors present for altering monsters will be useful for any DM. Lots of good things for DMs that work up homebrew material. I was tinkering around with other classes and prestige classes the first night I read the book. My players appreciate how similar the Trailblazer classes are to the 3.5 ones they already know.
[5 of 5 Stars!]