I've been following GTD for about a year - I use this term lightly as I haven't really done a Weekly Review properly before.
I've been good with my Action Lists - but I've been spending too long trying to find the perfect way to link Projects to Actions that I spent time tweaking when I should have been reviewing. I've now gone back to a sort of plain vanilla system - Outlook set up as per the Workflow PDF and syncing with KeySuite.
Well - I did my first Weekly Review and don't I feel good I printed out my projects list and used that to ensure all my projects had next actions, crossing off each project as I reviewed it.
I now feel squeaky clean and ready to face work tomorrow. In fact, I felt so energized that I did a ton of next actions (this time making sure I created the next NA as soon as I had finished it) and made some real progress with some of my projects.
So - if you haven't done it yet, you're missing out on an incredible feeling.