As a part of my recent experiment with GTD, I started using a hPDA to organize things in my life. Incidentally, I had to make yet another intense week-long business trip to Taiwan earlier this month, which provided a good opportunity to test out this new system.
I am happy to say that the ingenious hPDA works great for me, particularly when things are getting crazy with an international trip that was filled with dozens of important meetings in a week. The flexible formatting of hPDA worked much better than any app that I can find for my iPod Touch. Furthermore, the portability/robustness/responsiveness of a hPDA is way better than any electronic alternative. Although backup and syncing remains as an issue with hPDA, I think I am hooked.