I have taught with the sixth and seventh editions of this book since late 2003.
Generally, Mayfield does well discussing fallacies. Exceptions are noted below. She also does well describing the range of political viewpoints in America. This is important because many students are unaware of the range of political opinion in America.
The text pays much attention to the nature of observation and the relation between sensation, perception, and thought. A fair number of black-and-white illustrations are provided as subjects for detailed visual analysis. Students interested in the visual arts may like this.
The author refers somewhat too much to historical injustices against Native Americans. Native Americans have genuine grievances and some of the material is interesting, but students have expressed irritation at all the harping on the same tune.
The following comments identify errors of fact or incongruities that get in the way of teaching and learning. Some errors have persisted in two or more editions. It's true that one can make pedagogical opportunities of them, but that's no excuse for the author. Page numbers refer to the seventh edition.
Page 4, blue inset: the word 'skeri' is not an Anglo-Saxon word but a Proto-Indo-European root. 'Skeri' is the root of Greek 'kriterion,' which is the root of the English 'critical.' The text, then, is both inaccurate and unclear about the sequence of derivations.
Page 175: The author recognizes that an evaluation--Chapter 7--is a kind of opinion--Chapter 6. Separate chapters might be justified if each chapter had more meat, but they have little. They emphasize that the worth of an opinion/evaluation depends on the authority and motives of the person giving it, and that one's right to one's opinion does not mean that one's opinion is worth anything. I advise teachers to cover these two chapters in one class meeting.
Page 208: The quoted passage is probably not by Alexander Henry, for these reasons: 1. The use of the past tense clearly implies that the Native American nations are no longer are a significant presence. They were, however, significant and powerful in the colonial period, when the passage was allegedly written. 2. The style does not at all resemble that of other works attributed to Henry, which are extensively available on the Internet. 3. Most tellingly, the passage reads like 20th century English. Alexander Henry died in the 1820s.
Page 298: The directions for Part 1 of the chapter quiz use the term 'misapplied euphemisms,' but elsewhere in the text the term is 'misleading euphemisms'--confusing.
Page 299: Item 8 in Part 1 belongs elsewhere. The statement "There is virtually no tar in these cigarettes" is not a "misleading euphemism," "bandwagon," or "appeal to fear" fallacy. It's an example of vague or ambiguous language--'weasel wording'. The same is true of item 11.
Page 345, Item 11: Is this a ringer, or what? You can't say the passage is "nonfallacious." You can say that it demonstrates the "either-or fallacy," but that misses the point, doesn't it? A bright class might appreciate Woody Allen's gag, but it's a distraction from the exercise.
If this is the only book available, a teacher can use it to put together a viable course in critical thinking. However, I advise looking further.