Whilst AT1 covers the peninsular war, AT2 is much narrower in scope covering only the 100 days campaign.
Included in the book are army lists for the French, British, Dutch, Belgians, Nassau, Brunswickers and the Prussians.
The French list covers the units of the Armee Du Nord and has a list for the Imperial Guard as well. The French get a new rule for pick up/point value games which gives them a better chance of getting high decisiveness and other attributes when rolling for them in the main rulebook.
The British list is a fairly straight copy from AT1 by the looks of it. It was included mainly so that you didn't need both books to play.
The Brunswick forces get access to a lot of skirmishers and marauders, but no heavy cavalry and a very limited army list (There were only 8 infantry units and a couple of cavalry regiments present).
The Dutch/Belgian and Nassau list is quite plain with no real special units, but no real drawbacks either.
The Prussian list is another fairly generic set of units, however their command structure is fairly different from the other forces in the book. When rolling for random traits for officers, the Prussians have a chance to increase their command rating and get a slightly modified chart as well. In addition, Prussians have the option to buy Sub-Commanders for their Infantry Brigades. These function as a relay for the Brigade Commander allowing them to issue orders to units which would normally be too far away. Prussians also get a special rule called Prussian Square. When forming a square formation, most nations adopted a hollow oblong shape, but the Prussians formed a closed square with all the men standing shoulder to shoulder. This means that cannon fire against them has a higher chance of causing wounds, but allows them to form square AND shoot the enemy as they close in.
As with AT1, stats are included for most of the big names present, Wellington, Napoleon and Blucher all get a look in along with Ney, the Prince of Orange and a few others.
The book contains scenarios for Hougoumont, Plancenoit and Quatre Bras, though Waterloo itself is quite out of the question in 28mm scale.
The book also introduces some new suggestions for special rules for games. Probably the biggest change is to the "Square" formation. Columns form squares using the standard rules in the main rulebook, but Lines and Skirmishers have to take a command check from their Brigade Commander. Should they fail, they remain in their original formation. There are several modifiers to the roll (distance the enemy charges for example), but it makes it easier for cavalry to drive home an attack, especially on poorly led units.
Another new rule is the option to fire cannons at more than one target as you 'bounce' the cannonball. Similar to the Warhammer Fantasy rules for cannons, you can strike multiple targets if they are all lined up.
To recreate some of the battle of Waterloo, there are rules for Divisional Commanders (offering re-rolls to Brigade Commanders) and Engineers as well as weather effects. Cavalry get a semi-assault column rule which trades off a point of their Hand to Hand for an automatic +1 to combat resolution. It does however make them more vulnerable to artillery fire.
On the whole, the book is very well done (as with the others in the series) but I do have a couple of minor complaints. The changes to the square rule don't cover skirmishers due to a typo. I checked with the author and he said that the rule DOES apply to skirmishers. My only other complaint is that I would have liked more battle reports or info on refighting some of the other parts of the campaign.
For those of you with a more Central/Eastern European craving, a 3rd (and 4th) book is on the way with rules for 1812-13 and armies for Russians, Austrians, Saxons, Bavarians, Poles, Prussians, and The Confederation of the Rhine.
