Just as I was considering having my DNA tested for genealogy purposes, along came this book to take all the mystery out of the process. I have a medical background and am not unfamiliar with the difference between Y-DNA and MtDNA, yet there is so much more to know that she clearly outlines in this book. She has clarified what to expect at this point in the evolution of this as yet very young science, in terms of how to choose a company and what results mean. Her hyperlinks to resources are very helpful.
The second half of the book deals with social networking and its usefulness to the family historian, a subject which she also details in clear language and a straightforward attitude. The primary message here is, use it! It's not just for kids, get on Facebook, Twitter, UTube, and anything else where you may find answers to genealogy questions. She also tells us what NOT to do with some of these tools as well, such as giving too much personal information in a public forum.
The only caveat is that the author is clearly British and the book is written with a British reader in mind. Many references are to British archives familiar to a British reader and not so much to an American. That said, I had no difficulty "translating" to my American needs.
I first bought this on my e-reader and now am buying it in the print version because I know I will refer to it again and again in my research.