Kagan's book provides a very detailed overview of the coalition's military operations in Iraq during 2007. Like many other popular, and also very solid accounts of the surge (Ricks, Robinson, Kilcullen, et al), she addresses the shortcomings of the pre-surge strategy and the failures of operations like Together Forward II. However, unlike these accounts, she dedicates less time emphasizing the role of population-centric COIN in shaping the outcome, instead focusing more on the role of kinetic operations like Phantom Thunder. Additionally, she spends significantly less time focusing on the role of Petraeus, and instead points to the critical role Odierno played.
While overall Kagan does provide a detailed account of the surge, it's important to note a few caveats. First, her husband, Fred Kagan of the American Enterprise Institute, was one of the surge's architects. Therefore, Kim Kagan is hardly an objective or dispassionate analyst. Second, although extensively footnoted, a large proportion of her citations come from military press briefings. In other words, the organization tasked with implementing the surge is also the organization she relies on for much of her data.