there's not really anything to love or hate about this book. it's merely the documentation for the renderer. in reference to the previous review, this book IS available in html form if you purchase mental ray standalone, and it is also bundled with the docs of most 3d applications that include mental ray as a built-in renderer, such as Maya or XSI. buy it if you like to have a hard-copy of your docs around.
the book includes a cd with all the example shaders as well as some additional resources that mental ray programmers might find useful. overall, it is a very thorough, no-nonsense, documentation of the mental ray renderer.