Going into a biography, most of us have a basic understanding of core life events. We read biographies because we are interested in unique insights that (hopefully) biographers can provide.
The only real way to do that is by interviewing people and drawing out interesting details that haven't been published yet (for a dead person, you might draw from a recently-discovered journal) In this case, the author did neither. Which is not to say this biography is bad, but the price should reflect that