In Dynamic Characters, Nancy Kress, best known for writing science fiction stories, systematically goes through the process of creating compelling and realistic characters. She breaks the book down into three main sections: external, internal, and the characters' relations to the plot. The external section covers more than just looks and clothing. It also includes the choosing of names and the configuring of dialect. The internal covers everything from incorporating dreams and newscasts into a character's world views to establishing the distance between the narrator's and protagonist's thoughts. The last section focuses more on the types of plots that are available and how these plots can spring from well-thought out characters.
For someone who has never read a book on writing, this one would likely be informative. For anyone who has even skimmed through one before, this will only provide a limited amount of new information.
For me, it was moderately helpful. I found the chapters on creating pertinent dialogue, infusing that dialogue with the right amount of descriptions, and judiciously making use of descriptions to be helpful. Even more helpful was the intelligence dossier, which contained a long list of questions and characteristics to fill out for each main character, and the chapter on point of view, which gave great examples of how to slip back and forth from the narrator's thoughts to the protagonist's.
There were other chapters that were only marginally helpful, if even that, though. These would include chapters on avoiding stereotypical dreams and villains, unlikeable protagonists, and boring fights. I also feel like most writers can figure out how to avoid offending friends when they incorporate their faults into a book.
And all too often, Kress ends sections with some bland advice: use your best judgment. I understand that writers need to do this, but I don't need to hear it over and over again. Just stick to the examples, please.