Overall this is a nice book to have on your shelf, especially if you're a Christian classical homeschooler and you want your kids to understand logic. However, if you're only going to pick one or two books for logic for your homeschooler, the Bluedorn brothers' books Fallacy Detective and Thinking Toolbox are much better. Here's why:
1. Bluedorns are more concise. Both books have interesting writing style and are humorous. I suppose in certain senses, you might say they're similar in writing style. But the Bluedorns don't have as much clutter in their books. Their supplementary examples of dialogue or cartoons are necessary or helpful. Wilsons' chapters are cluttered up with "Dr. Ransom's travel anecdotes" and lengthy, sometimes silly, explanations of made-up creatures. While at first I thought it was a neat idea, and the illustrations are funny and whimsical, over time, we bored of all the little made-up creatures. In fact, I thought it wouldn't be helpful to remember the different fallacies. It's just 50-something more things to memorize for the flashcards.
2. Bluedorns are clearer. I got frustrated with the Wilsons early on, because I REALLY want to get better at logic, and their writing confused me at times! For example, each fallacy is illustrated, both with pictures and stories, with a little made-up monster that (somewhat?) acts out the fallacy. There is a picture of the monster with the name of the fallacy underneath, with a description (definition) of the fallacy. That's helpful. Then underneath that definition is a list of "alternate" names. I got frustrated when sometimes the fallacy names were clearly made up to fit the little made-up beast, but on occasion they would choose that made-up name as the main name of the fallacy, or as the alternate name. I don't mind if they want to make up names, but I'd appreciate it if they'd use the most common name of the fallacy as its main term, and if they want to include their own made-up name as an alternate, PLEASE make it clear that this is not an "official" name. On occasion the Wilsons were so busy being cute, clever, and creative in their writing that I honestly didn't even understand the joke or point they were making. Perhaps they were assuming that their readership is so clued up on their other writings that we would be able to make connections. I could most of the time, but not all, and that's not good writing.
3. Bluedorns were more credible. My husband and I have often commented that the elder Wilson is better at rhetoric than logic. Many times he is logical, and I'll bet he knows a lot more than I. But in his blog posts, he will assume or assert a position rather than prove it logically. His writing is powerful and persuasive (and certainly not PC, which doesn't bother me), but it can be distracting, and even lose his audience when he sometimes overstates his case or overplays his hand or distances readers by offending even those who want to like him. His descriptions of the little animals or his reactions to them were over-the-top at times.
For example of uncomfortable material (I wasn't really offended...), I felt that some of his subject matter, which would show up repeatedly in either his lesson or the practice exercises afterwards, was inappropriate for either youth (the age for whom this was written) or adults who are trying to live a holy lifestyle. There are jokes (granted, critical) about immorality; several comments about homosexuality, several about women in ministry, and numerous about drinking. I could overlook the middle two, since I agree with him, even though I wish he wouldn't emphasize the kind of thing he's always fighting on his blog with high schoolers, but hey. Whatever. But here's an example of the beginning and ending of Fallacy no. 34: Bifurcation:
It starts: "On one of my explorations in the southern tip of Mexico, I came upon a small outpost that had one seedy tavern. Upon entering that tavern, for my thirst was approaching significant levels, I asked the man behind the plank--stretched between two barrels--what my choices were. He said that I had two choices. What were they? I inquired. He said that I could have whiskey or air...."
and ends: "Oh, and in that Mexican saloon, I ordered tequila. I had to pull the bottle out of a GB myself, but I got the job done."
That just isn't funny, especially to a missionary who's seeing alcohol ruining the lives of people. It doesn't sound like Spurgeon. It's not a holy mindset. If they want to hold to Christians drinking, why can't they keep it out of a 7th-12th graders' textbook on logic? Why alienate part of your audience? This damages their ethos when it comes to other assertions they want to make. I can't remember the specific example now, but a few times, my husband and I disagreed with their answer key or whether or not something was a logical fallacy, because it had to do with a theological belief or practice (not a fundamental doctrine, but tangential) that the Wilsons hold to and assume others will agree with them on. So they point out logical fallacies in the opposing side with a quick one- or two-liner. The thing is, that we thought they were the ones with the logical errors. So that also damaged their credibility. They should have stuck with the best examples.
So clarity, concision, and credibility--the writing style would get marked down for those reasons. However, still in general, it's a nice book to have on your shelf and supplement your logic curriculum. It's just not the book to pick if it'll be your ONLY logic curriculum.