I found a dated podcast of David Allen, the author of Getting Things Done (GTD), with Merlin Mann of 43folders.com. I highly recommend the book, it’s a cornerstone to being productive. In the podcast, Allen admits that there’s a very low adoptation rate of people who start with GTD and end up using it. They include:

Not easy to get started- Try to put yourself in an environment where the GTD language is spoken.

Getting more dimensions– Keep learning. Keep rereading. One answer he gives is GTD connect.
High level issues (20,000 & 30,000 & 40,000- feet)- if you don’t address your high level goals “your system will become flat”.

You’ll notice  these are exactly the issues that I discussed earlier with Don’t Get Things Done. I’ll keep bring more solutions to these and other problems with GTD.