The book is a successful collection of the most popular tools appropriate for experts and all other interested people who already own a certain degree of knowledge with regard to the topic. In particular the statistical tools originally out of Six Sigma need some mathematical background to satisfy. Out of my point of view it's nevertheless strongly recommendable for improvement specialists and their respective management.
I really like this book as it presents a lot of Lean Management and Six Sigma tools in a nice and small book. But the US layout with a lot of text size changes, bold and italic printing and very narrow breaks is extremely exhausting while reading. It is definitely a great book if you just want to have a look on the exact meaning of a certain tool. It's quite small, too, therefore you can easily take it with you to get a sneak peek while moving around.