It really doesn't explain why they chose a book as their format over a searchable website or why they chose a 2 page layout, with one color inverted.

Spreading the content over 2 pages makes it very unusable. Displaying 2 pages side by side makes the content too small to read. Having every 2nd page color inverted makes it unprintable. It's also annoying if (like me) you invert the colors on your e-reader or PDF viewer.

I also noticed the index doesn't have hyperlinks to the content pages and it doesn't appear to have a working table of contents making it even more difficult to use on an e-reader.

I like the concept but the implementation has serious usability issues.