This book paints King David as a near perfect man. It portrays those who disagree with David as baseless, vile men who are bound to hell.
Keller inserts lush narrative phrases to make his case rather than citing biblical support.
I find particular blame with his depiction of Joab. Take for instance pg. 33, "Without any hesitation he stormed into David's presence, his countenance black with anger... angry charges tumbled out of Joab's mouth like chunks of molten lava erupting from a violent volcano."
Or pg. 92 (talking about David's sin with Bathsheba) "Being a party to this murder of an innocent man would give Joab the grim leverage of blackmail over the king for the rest of his days." This is a completely absurd comment to make. We don't know WHAT Joab was thinking. In fact, some studies point out that his running to the wall suggests that he was very against Uriah's death, but could do nothing because he couldn't ignore an order from the King.
Later he says Joab is not a man of faith in God the Almighty, pg. 187 - ignoring that it was Joab alone that rightly told David his census was a sinful act, that it was Joab who said, during a battle with his brother, "Let God do what is just in His eyes." It was Joab who was loyal to David and the kingdom, giving up his desires so they might prosper. Joab conquered the cities and had David come and claim them so David could get the credit. Even when Joab was killed he sought sanctuary at the horns of the altar.
Keller just tows the party line. "David was a good king." David WAS a good king, but that statement oversimplfies all of the issues.