That you're reading this review at all is proof, not just that you need (and will enjoy) this book, but that you appreciate the importance of language. You may already have a stack of books on language, yet you're still looking. That was my struggle too. After reading any of the other books for 10 minutes, I was ready to do something else; English can be boring. Those other books of mine have good information, but the effort to dig it out and find relevance is work. Enter Jack Lynch's book! :) Immediate improvement.
Where other books seem to be written by grammar police, this book is filled with useful and workable information and acknowledges that some aspects of the language aren't worth losing sleep over. The book is fun and I find myself enjoying the author's perspective as much as I do the information presented. Don't get me wrong; this is no quickie book on how to write well, but a thorough text on the subject. Yes, you still need your Strunk and White; having two quality references for comparison is always good, but this book has a permanent space on my desk, whereas my other language reference books are in the book shelf.
What I especially appreciate in reading the book is that it has improved how I think about what I say and write. Language is not just following some rules, but a means to clarify your thoughts to others. The book excels in this and it's not a specific topic within the book, but always just beneath the surface throughout. People pay me to help them get their message across and this book is priceless to me.