If writing non-fiction is an important part of your personal or professional life, reading this classic will be a sound investment. I read this book many years ago, when it was in its first edition, and its wisdom has had a profound impact on me. I can think of few experiences that have had such a demonstrably positive influence on my career (I am currently a professor of computer science). I have found Zinsser's sage advice to be applicable to writing technical papers, letters to the PTA, and virtually every other form of non-fiction.
Zinsser patiently instructs his readers on how to write about travel or science, how to conduct an interview, how to craft an effective lead and ending, and even how to get started. Along the way, Zinsser entreats us to omit clutter and cliché, strike out useless adverbs, adjectives, and qualifiers, incorporate active verbs, and strive for correct usage as well as unity of pronoun, tense, and mood. But the overriding messages are clarity, simplicity, and directness. Keep it crisp. Oh, and just like driving a car, always signal your intentions (keep that "but" at the beginning of the sentence).
Two specific pages in Zinsser's book have remained etched in my mind from the moment I took them in almost two decades ago. They comprise the most genuine and revealing demonstration I have ever seen in a book on writing. On those two pages (pages 10 and 11 in the first edition), Zinsser provides a glimpse at the penultimate draft of the very book you are reading, juxtaposed with the corresponding pages in final form; in so doing, Zinsser invites you to critically examine his own writing, while revealing something of his process. This was brilliant. Those few pages (penultimate draft plus final draft) are alone worth the price of the book.
The lessons in this comparison are profound: First, Zinsser himself practices what he professes, but more importantly, even he is prone to inflate sentences with useless verbiage. What Zinsser has beautifully illustrated is how his writing came to be so tight. It did not spring from his mind to paper in the form we see; rather, it was gradually shaped through repeated editing, much of it with the aim of removing unnecessary words. (One could say that he is more like Beethoven, who endlessly rewrote, rather than Mozart, who composed finished works in one stroke.) I immediately adopted this practice and to this day I devote several final editing passes to the removal of useless words. I can think of no other lesson that I have learned in my 22 years of formal education that has been so enduring and consistently useful.
In the past decade I have recommended this book to each of my graduate students, and nearly all of my colleagues; at times I have simply purchased a copy and presented it to them. Of course, such a gesture can be taken the wrong way. It needn't imply that one's writing is in desperate need of repair, but rather that the content is worthy of concise expression. It was in the latter spirit that I shared Zinsser's book with my students and colleagues, and I believe all have gained from it.
Do yourself a life-long favor and read this wonderful book. It won't take long, yet its lessons might forever change the way you write. Your readers will benefit, and you will benefit.