Dreams of Whose Father?

Does this book, which is generally a positive look at the President and Michelle Obama's history together, uncover the truth about Bill Ayers ghost-writing Barack Obama's book "Dreams of My Father," or merely repeat conspiracy theories about it? If it's the former, it's a really big deal, given that the book is one of the major accomplishments of the President's career and given that he claimed he barely knows Ayers beyond their work on a board together.