I very much enjoyed consuming "Getting Things Done" after hearing much hype about the system and being constantly exposed to the barrage of things purporting to be GTD-compliant and believe I understand why: it respects the reader's time.

*the advice is natural. The author notes that it's foolish to fight our natural planning tendencies and the way our mind works. We are distracted by both the giant and the tiny and the system recognizes the fact that both take up mindshare.

*there is utility at every level. One can implement full-fledge GTD including project-level views or just listen to tips and trips about filing and still get something worthwhile from the book.

*implementation options are manifold. The author goes over how to do an electronic, paper-based, in-between, and even an ad hoc implementation of the system. I think this universality suggests strength.

*full of useful assessment tools. The four-factor model for assessing priority is dead simple and obvious once one considers it but I felt I was wasting time with others where priority came before context.