Brian's style is unusual, concise and unpredictable... all of which makes this book a great deal more fun to read. You can buy much bigger books about public speaking, but they probably won't contain any more useful material. This is concentrated stuff, and all the better for it.
It's is a book that won't take long to read, but you'll want to come back and skim through it frequently. I've owned the paper version for some time, but I seldom have it with me when I want to do some skimming! (On the train on the way to a speaking engagement, for example.) So I'm delighted it's now out in Kindle form, which means I can have it on every device I own.