In this book RFK is protrayed as a really virulent anti-communist bully (his family were particularly close with Joe McCarthy, RFK went to his funeral) who was incapable of dealing with the concept of a communist regime being less than 100 miles from the American coast (and who willingly gave the CIA permission to go after Castro, no questions asked).
In addition, he seems to have got into law school (and his Department of Justice job and New York Senate seat) because of his family money and history, and doesn't seem to have been all that good a senator. In addition, while he was Attorney-General, he came across to me at least, as someone who:
1) Couldn't explain himself very clearly to others.
2) Seemed to believe that you could overcome internal problems by belittling people who didn't see things the way he did.
3) Wanted to throw money at managerial problems to make them go away.
Was he sincere about the plight of the poor? Yes (especially in later life), but that doesn't overshadow the interpersonal, managerial, and other skills that he seems to have had for most of his life.
Incidentally, I'm not sure that the author was particularly skilled either. He had a tendency to repeat ideas to unnecessarily reinforce points he was trying to make during the book.