This is not a book, it is a religion, and I am a convert. I found it to be different from other time management books, because of its unusual philosophy. Instead of starting with the system, it starts with the goal: to make you feel relaxed and powerful. Everything in the book is about that, really. The book is about creating simple systems of time and task management that keep you from worrying, so that when you want to work, you can work with a "mind like water" and that when you want to rest, you can also do that peacefully. And the systems really work, if you are willing to make the sacrifices they entail. You need to spend about three full days to get started, change certain little daily habits (jot down every "Oh! I have to remember to..." thought, etc.) and then (the hard part) you need to commit two hours every week to reviewing and maintaining your task/project management system.
Every once in a while, I read a book that dramatically changes my life. The last one was Design Your Self, which set me on the road to an organized life. Getting Things Done finishes the job that book started. I've been following the systems for about a month, and the differences have been dramatic for me -- I used to spend a good part of every day overwhelmed -- scared to death that I had forgotten something important. But not anymore -- everything is handled, in neat little containers, and my hundreds of projects are just little tiny tasks that I can do whenever I feel like doing them, with a clear, worry-free mind.
Time will tell if I can keep it up!