I have tended to prefer non-fiction published by academic presses, and I tend to expect about 30% of the book to be notes/sourcing. It's a very superficial way to judge a book, and I've been suckered by bad sourcing (most conspicuous example being http://en.wikipedia.org/wiki/Arming_America:_The_Origins_of_a_National_Gun_Culture). It's not a deal-breaker and it's not my only metric. I'm really glad it's not my only metric, because this book doesn't have any scholarly apparatus at all.
I've posted before about the weird blogstorm in December about whether genealogy blogs should have citations, when they should have them and the implications of not including them. Every time I try to articulate what I think about this, I find myself rhetorically paralyzed, so mostly I've given up and intend to avoid any discussion on the topic -- no matter how reasonable and/or well-reasoned.
This is a wicked fun book to read. If you don't give a crap about scholarly apparatus, it is one rollicking good story after another: about the author's own heritage, about our president's Irish roots, about our First Lady's ancestry, about the connections between Al Sharpton's ancestry and Strom Thurmond's ancestry, about the Unclaimed Persons project, about adoption stories -- and on and on and on. Because Smolenyak has spent a huge amount of professional time tracing living descendants (for the military, for Unclaimed Persons, for celebrity projects, etc.), it's a lively tale even for those not particularly interested in genealogy. If you _are_ interested in genealogy, it's a field-spanning tour, even including a chapter of who might be the King of the United States if Geo. Washington hadn't squashed that idea right from the beginning.
Smolenyak makes an ardent case for resorting to paper without a foolish resistance to electronic resources. As with my favorite non-fiction authors, she is a crucial part of the story: how she got brought into a project, what her process was, how she engaged with other people in the work and what their contributions were, and how it was ultimately presented (often on TV); if you don't care for a strong authorial voice, this is not a book for you. Many of Smolenyak's stories start with "googling", and proceed through the use of online resources (indexes and digitized images), ending with her project-managing local researchers to get copies of paper records. When the records are within a few hours drive, she might go herself. In cases like Michelle Obama's ancestors, she traveled further to have the time to really delve into the archives.
Smolenyak describes her research process as "layered" (what I call iterative) and her position within the process as the hub of a wheel where other researchers are the spokes. This is genealogy at some level above "professional". But it's a fascinating viewpoint, and we're lucky to have her.
It should be obvious by now that I think you will have a blast reading this book (with the exception of people who do not like a highly-present authorial voice), learn a fair bit in a remarkably painless way, and develop a new perspective on history/genealogy/project management. Also, celebrities! People lying about their age! Tons of fun.