Although this is a bit out of date now, these are very useful for bits of information about using the software that you just either forget or have yet to find out about. Mostly a really good memory would mean that you would never have to look up anything, but life now means that you have to remember so many other things, like PINs etc that the available space in the head is not limitless.
I do like the simple layout and the diagrams are excellent to use, so I have a full set of all their little booklets. My family also found them so useful that when they moved on, I bought them their own copies!!!
Like most Mircosoft software, there is masses of stuff included that most of which we will probably actually never use. At least it has become a sort of "World Standard" against which other programs are judged.