Unfortunately, whoever prepared this work obviously didn't bother trying to actually read it, in particular on a mobile device. PDF viewers, by and large, use the single largest page's size to calibrate their zoom levels. The final page in this book is huge (roughly 8 normal pages in size), which means that every PDF viewer i've tried starts out with the normal pages zoomed out really small (so that the single largest page takes up one screen). My tablet-based PDF viewers are literally incapable of zooming in far enough to make the normal-sized pages readable on a 10-inch screen.
The only fix for this is to use your system's "print to PDF" feature to "print" out all of the pages except the last one (i.e. pages 1-71), and then to read that copy.
Other than that, i'm sure it's fine, but jeez, people - try reading what you're selling!
[2 of 5 Stars!]