This book is a good resource for looking at how characters, the emotions they portray and in what viewpoint (first person, third person omniscient, third person limited, etc) to use, and it certainly complements the other books quite nicely. I have read all of the "WGF" books save for the one on revision and see them all as a great investment.
For this particular book, Nancy Kress does do a good job of exploring each element in detail. Like the other books, it is largely an overview of each concept, and, like the other books, she does hit on some similar aspects that the other books cover more extensively (how could she not? All aspects work together to create a work of fiction.) That is to say, the other Write Great Fiction books all cover every aspect of a piece of fiction, but mainly discuss how they relate to the given topic they wrote their respective book about. So brief overviews are found in the other books and each aspect is covered extensively in the given work. So "Plot" focuses on plot while giving smaller and more general explanations of characters, description, dialogue, etc. while "Dialogue" does the same with plot, description, characters etc. while keeping the focus on dialogue and so on and so forth. I would recommend a would-be author grab all four of these books, as this would then allow them to see the whole picture.
My main problem with this particular book is that when she gets to the section where she delves deeply into first person, at one point at least she goes into a small rabbit trail about why some readers don't like and will never read first person. Apparently they're willing to read books but not willing to suspend their disbelief that the character narrating the work was an active participant. It makes absolutely no sense to me but I am not going to judge these people. My problem with this is that she goes a little bit longer talking about this than what the situation merits, spending at least a page or two on the subject, yet she says NOTHING of authors who write their books in the present tense, even though this style is easily as equally jarring and disengaging as first person, actually more so in my opinion. Why she ignores the pitfalls of writing in present tense yet shows the pitfalls of first person, second person, third person, first person plural, third person plural, multiple first person, multiple third person, hybrid, (and there's more but you get the point,) is beyond me.
All in all a good book and I would recommend it.
Edit on Saturday February 14th: I would also recommend "The Complete Writers Guide to Heroes and Heroines: Sixteen Master Archetypes" by Tami D. Cowden, Caro LaFever and Sue Viders.