While this may not be a full scale biography, but more an impressionistic rendering, it is an amazing book, and not to be missed.
It is particularly relevant because Ellis was one of the first to recognize the facts regarding Sally Hemings, and clearly fully appreciated how much that circumstance enriched the contradictory character that was Thomas Jefferson, for the paperback edition of the book a suitable addendum pertaining to this relationship was added, and corrections made wherever necessary in the text.
I'm finding that any of the still in print biographies, who missed this point make themselves irrelevant right away for the exact reasons Ellis tries to capture with his title of the book, namely American Sphynx. The full complexity and the inner contradictions of this man's character are only just beginning to be understood. But this book is as good as any, and better than many others to begin to get a handle on this perhaps most elusive of the founding fathers.
What I do miss is a deeper exploration about the issue of Jefferson and the Bible, which is also profound and contradictory on many levels, and I've never found a satisfactorily exhaustive treatment of it anywhere, except for some hints in various discussions, as well as in Gary Renard's books, of the remarkable parallels between the excerpts from the Bible of Jesus' sayings, and the sayings of the Thomas Gospel, which to my mind suggest a profound if largely unconscious connection with his subject, even if his materialistic interpretation of him in my belief shortchanges the subject.