I've read both of President Obama's books, Dreams from My Father and The Audacity of Hope. I recommend them to anyone who has an interest in politics generally or Barack Obama in particular. I doubt that reading the books will change anyone's basic opinion of the President and his political views. However, after reading them the extreme perceptions of some are likely to become more reasonable.
One issue that has generated speculation among some conservatives is whether Obama wrote the books himself. That's to be expected, given that anything that diminishes him is grist for their mill. The most comprehensive of these arguments against his authorship can be found at American Thinker. The first article posits that Bill Ayers helped write or re-write parts of Dreams; the second article argues that Jon Favreau, Obama's senior speechwriter, wrote most of Audacity.
Obviously, I can't make an authoritative statement that Obama wrote every word of both books. That's rarely true of any author. Manuscripts are reviewed by friends, relatives, and researchers, virtually all of whom suggest changes. Books are also reviewed by agents and edited by publishers, sometimes extensively. However, to falsely claim that you wrote a book, except for the contributions of others mentioned above, is a fraud.
For a president, it's a fraud that will inevitably damage him. For example, John F. Kennedy's image has been tarnished by revelations that Profiles in Courage was written mostly by Theodore Sorenson, his speechwriter and confidant. (That didn't deter Kennedy from accepting a Pulitzer Prize for the book.) Barack Obama is a highly intelligent man who certainly knows all this, and that leads me to believe that his claim of authorship for both books is valid.
However, there's no question that the writing style in each book is different. Dreams is written in a much more literary style than the second book. It's full of flowery descriptions and occasionally overwrought, sometimes inapt metaphors, much like an overly chatty novelist might write a non-fiction book. Audacity, on the other hand, is written in a much more straightforward style, like an academic might write a book on politics and public policy. Even in parts of the book that are about his personal life, that more direct and economical style prevails.
Dreams was first published in 1995. In the preface to the 2004 edition, Obama admits to wincing now and then at the writing style of his youth, and he was tempted to shorten it by about 50 pages (but didn't). He was right about that — the book is too long, and certain parts, especially on his time as a community organizer in Chicago, could have profited from a trimming. It covers his life from birth to his entry into Harvard Law School, when he was about 27. The genesis of the book was the publicity he received as the first black president of the Harvard Law Review. A publisher and others thought his life to that point would be worthy of a book, and he was paid an advance for it. It took a long time to finish, as it turned out.