Nope. Haven't used one since I got a Palm III about 11 years ago. Then went to a Palm VII (got it free from Palm to be a beta tester). Then went to a Garmin iQue 3600 (Palm based). I synchronized all of them with a work PC and my Mac at home.
Latest job provided me with a Blackberry 8700, which I continued to sync with work and home computers. The nice thing with the BB on the windows side is you can set it up to wireless sync with exchange. So it's always up to date and backed up.
For the last month, I've been using my iPhone. Manually synchronized with both computers. Can't wait for the iPhone to support ActiveSync. (hoping that it works on the Mac side as well).
I ditched the paper planner for a few reasons. I travel a fair amount for work, so having one less item to carry was a benefit. Also, the electronic device is easier to keep updated with contact info, etc. Plus, I need to share my calendar with a few colleagues. Doing it electronically is much easier. My devices have always been password protected. So if I lost them, the data is relatively secure. Not so with a paper planner. Plus the electronic device is backed up frequently. Also, the newer devices don't lose info if the battery dies. Just recharge and go.