The tips are simple and it is possible to implement them immediately.
Many books are first you go through a self analysis of your priorities rather theoretical and long. Allen takes the foot against these methods starting from the mass of the tasks you have to perform. This allows you to start after a few hours and feel an almost immediate decrease stress. This teaches you the same time to clear your mind of unnecessary things and be more focused in working on one thing at a time (the multi task is a decoy)
So pragmatic, easy, fast and efficient.
Once you've seen that you can quickly multiply your efficiency, it will be time to look at the order of your priorities in life. You will also clear the time to do it! But this part that is not the subject of the book.
In short, this book is a must. Widely most effective of all that I could see.