What is the Job of a Biography reviewer?

When the new biography of Calvin Coolidge by Amity Shlaes came out I did a post  criticizing the two most prominent reviews of what I thought was an excellent book.  The NYT and the New Yorker's reviewers put out reviews which showed very little evidence that either had read the book.   They both seem to have written the review with conclusions already written.    Commentary Magazine includes a review of the book in the April issue by historian John Steele Gordon.  Unlike the two mentioned in my March 14 post - Gordon took his responsibility seriously.   He dealt with the substance of the book.   Coolidge was indeed a person of his time but his career offers some insights that current politicians could learn from.   Had I read the Gordon review before reading the book, I would have been encouraged to learn more about Mr. Coolidge.   Isn't that the job of a reviewer?  Yes, it is.