The thing I love the most regarding this campaign is not the characters or plot.
What I truly love is how it deconstructs the plot regarding the First and Second War.
The First Chapter shows us that, in a war, some people will do anything to survive if pushed far enough. Honor, decency, loyalty to others and one's nation be damned. Zarach realized that if the survivors were to find out about what truly happened during Stormwind's fall, it would demoralize them.
The Second Chapter is a good following to this. While everyone else is ready to fight to protect the kingdom's memory, Zarach is the only that knows that said memory isn't as pristine as the others think. That the survivors have no idea that some of their fallen comrades were, in truth, cowards and traitors.
The Fourth Chapter shows what really occurs if most of your strategies are based on cavalry charges and having faith that the Light is with you. I gotta say that Maraleth's remark about Sir Lothar's death, while a low blow, it felt somewhat satisfying. The Alliance only won the Second War because there was dissension among the Horde's ranks, it didn't have anything to do with the Light or the fact that justice was on their side.
The Seventh Chapter, the final one, shows the fate of most survivors of a war (and Zarach survived two). There is truly no glory gained for 90% of the survivors. Yes, Zarach is still alive, but what does he have left? His family is buried on a island, he is tormented by the guilt and secrets that he had to keep from everyone else, he has seen that both Alliance and Horde have their own sins and faults. To the eyes of the commanders, he is pretty much a nobody, just a random priest that managed to survive two wars. He is so far in the deep end that all he can do is wait for another war to occur, because what else can he do?