Not as engaging or interesting as some of the histories of the Knights Templer or Knights Hospitaller. The focus more on the military aspect makes sense, as unlike the other orders the Teutonic Knights were in near continuous warfare on crusades against pagans in Eastern Europe. In a sense, it became a 'safe' crusade, offering the noble pursuit of chivalry, a code of behavior taken to ever more romanticized and unrealistic heights. Despite it being a book on the Knights, the situation's complexities require a rather thorough explanation of how the local cultures functioned. Copious detail explains the myriad truces, papal officials, backstabbing, and political games that went one. There is an abundance of maps to explain major changes in control of the region, and the castle of Marienburg is described in excellent detail.
The biggest problem with this book is the sheer complexity of politics in the region. From the Piast dynasty, Rus' princes, pagan tribes, etc. the names and rulers quickly pile up and never seem to create a sense of cohesion or definite states. Given how complex the actual political landscape was, this confusion probably reflects the reality.
Mentioned frequently throughout the book is the perspective of German historians seeing the Teutonic Knights as noble warriors of Christ, and Polish and Lithuanian's seeing them as bloodthirsty, rapacious bandits. Given Prussia then Germany's proclivities towards aggression up to WW2, the Knights have been viewed as a cultural fingerprint of German life, an early aspect of its imperial expansion and brutal subjugation. Specific perspectives like that emphasize just how centuries of political and cultural conflict shape the way we view the past.