As someone who actually is Scots-Irish or Ulster-Scot, I would happily recommend this book. It is an aspect of history that attracts far too little attention, despite the influence the Scots-Irish have had on the world, especially in North America. An influence that for too long, was virtually forgotten.
"A Yank in Belfast" questions a few aspects of the book, such as their defence of the frontier,"...Webb goes too far in defining this attribute as somehow ethnically unique." I would say that Webb actually has a point. If you properly understand the history, culture and character traits of the average Scots-Irish settler, you would know that they were ideal frontiersmen: Independent; self-reliant and unafraid to fight for what they believed in.
Their religious beliefs, through the generations had also moulded many of them into quite radical political thinkers and they played an influential role in rebellions on both sides of the Atlantic in the 1700s. A German captain fighting on the side of the British during the American War of Independence even said, "Call this war by whatever name you may, only call it not an American rebellion; it is nothing more or less than a Scots-Irish Presbyterian rebellion". George Washington said, "If defeated everywhere else, I will make my last stand for liberty among the Scots-Irish of my native Virginia. All of this, combined with such things as their influence over the Declaration of Independence (which a Scots-Irishman printed) and many other things I could list, I think supports James Webb's comments about the importance / influence of the Scots-Irish in the history of the US. The qualities / culture / history of the people, made this possible.
The comments of "A Customer" I feel say more about his / her stereotypical ideas and prejudices against his / her Scottish Lowland neighbours, than they do about James Webb's book, or the Scots-Irish. I would suggest that you would have been better spending your time outside grinding your axe rather than reading a book about people for whom you clearly have "issues". Maybe it's time you got over, whatever your problem is. You have made various accusations & criticisms, including Webb's "ignorance". Having studied 9000 years of history that would be somewhat relevant to the contents of this book, I would suggest that readers simply ignore the historical ignorance revealed in your comments and enjoy the book.
This is an important and interesting aspect of history that people seldom have the chance to read about, which will make it all the more surprising!