While I disagree with the title (how can they be unknown facts if they are written in a book?), the information therein was pretty good. Wish there was a little more detail in some of them; the author did make each 'fact' a small paragraph, so adding a little more detail wouldn't have disrupted the book. Sometimes he left out the 'where' of the fact which would have made it generally more interesting.
A few typos, as can be expected, but nothing really out of the ordinary for a self-pubbed ebook.
Many facts were repeated throughout book. There were many spelling and grammatical errors. One thing I did like was the links to the websites while reading the book on my Kindle.