Here's a review from the Times:
This is not a book about White House table talk, the president’s spiritual values, his relations with Mary Todd or even his deep-seated opposition to slavery. It is about how Lincoln led the nation to victory: his formulation of the country’s war aims; his mobilization of public opinion; his diplomatic and economic leadership. Above all it is about his oversight of military strategy, in short, his duties as wartime commander in chief — duties that Lincoln defined and executed for the first time in the nation’s history.
I contrasted Bush's failures with Lincoln's success in this post from 2006
When you look at the functions listed for wartime C-in-C, it is pretty obvious that GWB has done a woeful job in Iraq. I'm not sure he deserves passing marks on any one of them.