An excellent work. Other reviewers have criticized the prose style, but I found it highly readable. Connelly's focus here is on the period of the Army of Tennessee from the formation of the Tennessee state army under Gov. Isham Harris to the retreat from Kentucky after Perryville (although title notwithstanding, the Army of Tennessee did not go by that name until after all of the events of this first volume). Connelly chooses to focus on the (barely-functioning) high command structure of the army, rather than on its common soldiers. Pretty much all of the relevant generals come under criticism from the author (Pillow, Polk, A. S. Johnston, Beauregard, Kirby Smith, Bragg + Gov. Harris). Bragg comes off slightly better in this work than in others, with a lot of the faults of the Kentucky campaign laid at the failings of Kirby Smith, Polk, and the Confederate War Department, although Bragg does take some blame for poor planning and lack of strength of character.
The main issue here is the paucity of maps - there's a partial theater map at the beginning, a couple for the Kentucky campaign, and one for the initial dispositions at Shiloh, but on the whole there are too few maps for a work covering such a vast geographic area as the Confederate 2nd Department.