First off, I'll start by saying: "Don't hesitate, JUST BUY IT!!"
This is one of the best investments you'll ever make. I've read "Getting Things Done", got hooked, then proceeded to read D.Allen's other book "Ready for Anything" as well as source and listen to the CDs "Getting Things Done fast". I can honestly say that this book and the whole "GTD" way of thinking has changed my life.
Before this book, I was a procrastinator who was almost always late for deadlines and often unreliable with commitments. I read a variety of books on time-management, productivity and procrastination-motivation, but none as influential as this.
I have been using GTD for about 2yrs now, I am highly organized, productive, with all my commitments outlined in an organized and trusted system - nothing slips through the cracks any more. I've set everything up in Outlook, have my categories such as @home, @computer, @out etc and just keep ticking away Next Actions and completing projects. I synchronize everything with my smartphone (HTC S620) and have the whole system (calendar, tasks, contacts, notes) portable with me wherever I go. My inbox remains empty and all my emails are correctly processed. Finally, I've introduced the habit of the Weekly Review and now look forward to blocking the outside world, once a week, to take stock and reorganize myself and prepare for the week ahead.
Since I got this book, besides being productive and organized, I find myself meeting all deadlines and feeling much less stressed.
Like I said, JUST DO IT and buy the book! What you'll get is one of the best and most practical books on personal productivity!!!