I first came across this system when setting up LifeBalance for the first time - there's plenty of discussions of how to use LB to implement GTD in the LifeBalance fora. Then, not very long ago, I found 43folders, via But She's A Girl. I read a lot of the introductory material then and was attracted to the sound of the system and interested that it seemed to have so many geeky converts. BSAG also started writing about the system and I thought "What the hell" and added it to my wish-list (which I now realise serves as a "Someday/maybe" media list for me :) ).
Now I've read the book and I think my assessment from reading around it is right - some parts of it really chime with me, particularly the "Next action" philosophy. Quite often in meetings I find that I'm the one saying "So what are we actually going to *do* about this?" at the end. I find if there hasn't been a decision like that I end up feeling like I've wasted my time. I think the new discipline which will be most useful for me is the weekly review though, because that's a habit that I don't have and that's where my personal systems have tended to fall down. They do fine when I've just set them up but then I neglect them and then I stop trusting them to have everything in and it's a downward spiral.
So, I'm going to try and do most of my set up tomorrow and finish on Tuesday at work and we'll see how it goes. If I learn anything interesting, I'll try to let you know :)
Also, completely unrelated, but I want to remember to install it at work, I've just discovered that there is a Firefox BugMeNot extension. It puts BugMeNot into the context menu for form text boxes and fills in the resulting username password for you if it can. Neato.