This book is fluffy like a cloud. It's full of fluff content that could be condensed into a much smaller book. The author needed to fill 280+ pages, so this is what you get.
Furthermore, “Getting Things Done” was not an easy book to ‘get done' at all. In fact, I started reading it, TWICE, and both times, could only crawl up to 30% of it before moving onto more interesting books. I'm not alone in this, with 2 other friends barely getting through the first 20% of ‘Getting Things Done'.
As a book, it's boring, and like I said, fluffy.
But, as a concept and guideline, it's very good. Concepts such as completely dumping (from the mind) all of the things you need to do (or want to do) onto paper, is quite useful. Along with mandatory weekly reviews and re-organizations, prioritizing tasks more efficiently, and the 2 minute rule (if you can do it in 2 minutes, do it now!).
Yet, in book-format, you feel like you are falling asleep reading a boring school text book. This should be taught in a video-product, or from seminars, with help from people.
If you want to learn the concepts, look for videos on GTD on youtube, or simply find a summary of the book. I bought ‘Cheatsheet: Master Getting Things Done in 2 minutes', and got all of the concepts needed from there.
Research has now proven that a significant part of your psyche cannot help but keep track of your open loops, and not (as originally thought) as an intelligent, positive motivator, but as a detractor from anything else you need to want to think about, diminishing your capacity to perform. ~ David Allen