I never use any of the four PDAs that I've got/had. The most useful was the Psion 5 as it had a keyboard - I used it to write university essays on the train. If you're still after mobile email and so on, consider one of the new smartphones such as the Nokia 7650. It has all the basic PIM functions and since it's a phone, you are more likely to have it with you when you need it.

The question of how useful PDAs are came up on Slashdot recently.
http://ask.slashdot.org/askslashdot/02/11/24/0224251.shtml?tid=99