The book is mainly about the principles of writing well (clarity, simplicity, brevity, and style) and the author's reflection on different types of writing, such as memoirs by known and moderately known authors. It doesn't provide the mechanics -- do this, don't do this, and here are bunch of "before" and "after" examples. I enjoyed the book nonetheless. It's more like an introductory lecture on writing nonfiction, get you motivated to write and to think about what makes up good writing. I suppose the author did give one advice -- look at something you've written and cut about half of it out. Your writing should be better.
The book provided a lot of examples of good writing and excellent writing by applying the techniques mentioned. Even for someone who is only looking to improve her writing (not necessarily get published) would benefit from this book.
I practice the advice of cutting out adverbs and adjectives. Is the writing still saying the same thing with less words?