In terms of actual lessons, I think these chapters (24-31) have been some of the most helpful. I thoroughly enjoyed her examples in chapter 26 about "affect" vs "effect," (this is something that many have tried to teach me, and so far all have failed). The Grammar Snob put it into terms that I can understand (kudos to her there); unfortunately, I have the feeling the lesson will be gone in a few days (not her fault though; this lesson never stays w/ me long). I also appreciated her focus on Hollywood throughout these chapters because my useless Hollywood trivia needs improvement as well.
One thought popped into my head several times when reading these chapters (especially the ones on predicate nom., conditional statements, etc). That was that many of these rules are ones that I learned in German class instead of English. I knew them in English, but not in terms of actually stating the rules (I only knew them because English, believe it or not by my superior grammar [sarcasm by the way], is my native language). And that was officially the most complex ( ) expression I have ever made; good luck reading that one. Anyways, what I'm trying to say is that I think it's a shame that (from my experience) Americans speak English, but they usually know very little about why they form sentences the way they do. It isn't until we learn a new language that the rules of our own become somewhat clear. Just a thought I had.