This book by Christie Golden continues the process of "novelizing" the classic Warcraft II computer and its expansion, Beyond the Dark Portal. The story centers around the characters Khadgar, Turalyon, Alleria, and so forth, and tells the story of the human expedition to defeat the Orcs in Draenor once they threaten the world of Azeroth a second time.
Golden, as in her earlier books, does a fairly good job of characterization. She tends a bit towards the "soft, misunderstood" side (she's not that great at making complex "evil" characters), but generally tries to create a decent characterization for the purpose of the story.
The weakness is in Golden's execution of both the story and setting. Although Golden didn't really have control over the sequence of events in either, it is really in her descriptions that the story shows its weakness. Golden is not great at describing either battles or greater strategic warfare within this novel, but more to the point, she fails to capture the SIZE and grandeur of the conflict. Remember, this is a war that devastated the greater part of a CONTINENT, in epic battles of warfare and magic - yet with Golden, you never really get a good feel for its size and scope.
I would strongly suggest you get this from a library first, before deciding on whether or not to buy it. Golden is a decent author, but she is clearly not the best within the Warcraft novel genre - that belongs to Jeff Grubb.