I like Steven Pinker's work quite a bit, so I picked this up despite the insufferably smug subtitle: "The Thinking Person’s Guide to Writing in the 21st Century".
On the other hand, for those of you who doubted I was a "thinking person": you will now have to admit it. Because I read this book. Ha!
Many of Pinker's trademarks are here: the sense that the chapters are slightly adapted from college lectures; a decent amount of humor, including amusing comic strips that illustrate the point he's making; a forthright honesty in presenting somewhat controversial notions. (He drives some folks crazy on this last bit; see below.)
Pinker is, by training and employment, "offically" a research psychologist. In fact, he's a wide-ranging scholar, willing to investigate and explicate whatever strikes his fancy. This book might seem to be a leap away from his usual science-related topics. But it's really not: he has enough applied linguistic creds to chair the Usage Panel of the American Heritage Dictionary, which he's done since 2008.
So this book is a scientist's take on what makes writing good and bad. What sets it apart from classic style manuals like Strunk & White, et. al. is Pinker's willingness to get down into the technical linguistic weeds, and introduce the reader to syntax "trees", which modern linguists use to parse (or fail to parse) sentences into their component parts. (Which you do unconciously when you understand "The boy stood on the burning deck", and are flummoxed by "Stood boy deck the on burning the."). Pinker shows how some poorly-constructed sentences may be grammatical, but generate ugly trees.
But most of it is pretty straightforward advice to writers on how to avoid stuffiness, vagueness, opacity, and other bad things. Pinker is no pedant, peddling ill-conceived rules: go ahead and split that infinitive, friend, if it makes your sentence work.
On the other hand, he warns you away from usage that might be technically correct, but … well, here he is on "literally":
The "figuratively" sense is a common hyperbole, and it is rarely confusing in context. But it drive careful readers crazy. [pas: but not "literally" crazy.] Like other intensifiers it is usually superfluous, whereas the "actual fact" sense is indispensable and has no equivalent. And since the figurative use can evoke ludicrous imagery (e.g., The press has literally emasculated the president.), it screams, "I don't think about what my words mean."
See Nathan Heller in The New Yorker for a contrarian take on Pinker. (Interesting source, since E.B. White, of "Strunk & White" fame, was a New Yorker guy for so long.) Rebuttal here.