Most of the books about productivity I have read recently have treated the symptoms of the wandering mind, rather than the cause. For example, meditation is said to give you better focus. But why is your mind so pre-occupied to begin with? Because you have a lot of shit to do! Getting Things Done treats the cause of your lack of focus, by organizing you so that your mind is relaxed because it realizes it doesn't have to pump you with reminders all the time.
Books about organizing yourself aren't fun. There's nothing exciting about improving your organizational systems, and so the book was not a page turner. But the productivity tips were outstanding. I'm in the process of implementing some of the suggestions for getting organized, as I suspect they will be very helpful.
Your mind can't help but remind you over and over about things you mustn't forget. But when your mind knows that you won't forget something, because it knows you will get to it before it must be done, it no longer needs to remind you. This sets your mind free to unleash itself on the task at hand. The book is all about setting yourself up with a system that ensures you get to stuff before it needs to be gotten to.
If you are looking to improve your ability to organize and focus, I highly recommend this book. You don't even have to do all of the tips; I'm not. But some tips will probably strike you as improvements and so the book will be worth it just for that. You will probably also find that you're already doing some of this, but not perfectly. This book will help you perfect your systems based on the idea of setting your mind free.