I was surprised at how little I heard about Lafayette in this book, though with an audiobook there is always the possibility that I drifted away for key parts. There was much more about Washington during the Revolution and that war in general, much of which I was not so interested in.
I have been a fan of Sarah Vowell, especially her book The Wordy Shipmates, which I found instructive and funny. The importance of Roger Williams in our history took on new meaning for me. In this book the humor seems to be limited to a sarcastic or sophomoric phrase thrown in at the end of many explications.
At the risk of piling it on, I will add that I find the practice of having well-known actors say the parts of particular characters to be distracting. Much as I like John Slattery, I found his French-accented Lafayette to be pretty irritating.
Sarah Vowell, Lafayette in the Somewhat United States, Riverhead Books, 2015, 288 pages (I read the audiobook). Available in the UVa and public libraries.