This book is a must for anyone who wants to master software design. It teaches you many techniques and principles to help you on the task of refactoring legacy code (with tests). Even if you are writing a software from scratch, you’ll definitely get to a point where your code will become legacy and difficult to test and to deal with. So I’d definitely keep this book by my side. Besides all that, it kind of helps you see legacy and rotting code from a different perspective: it isn’t just a rotting mess, it’s an opportunity to improve the design of the system, help your teammates, learn software design techniques and keep you motivated. The only cons is that many techniques in this book might be outdated, but you never know when you might need it.