I've had several PDA's through the years. My first one was a Sharp Wizard....they were about the size of a 12" PowerBook....ok....a little bit smaller....and were 512k memory...Man that was more than the desktop I had in highschool had...WOW!
Anyway..I poured coffee into it one day and took it back to Circuit City and since they didn't carry it anymore, and I had bought accident protection, they gave me store credit for the original price....
Anyway. A few years later I tried another Sharp PDA that had a built in phone-modem. It was about the same size as some of the larger PDA's these days and I could check my e-mail at a lot of different locations. But, frankly I didn't use it all that much so I eventually sold it on Ebay for about what I paid for it.
Next I bought a iPac that was pretty much cutting edge for it's time but again, after a few months I just realized that it was too freekin big and I really didn't need it.
My last one was a Palm Tungsten E. It was small and had pretty good functions but I just can't get into using them.
I think for me it comes down to the fact that I really operate pretty well without a datebook. I find that an address book works just fine for me for phone numbers....that and my mobile phone keeps all that information for me anyway....and the wireless features like web-surfing and other little extras cost too much, in my area anyway, for me to pay for them.
So I'm back with what I've always gone back to between PDA attempts.... I have a little black "Molskine" notebook with an elastic band that holds it closed that I use for everything. I use it for a few months then buy another one.
Paper and pen....does everything I need for $10 a pop a couple of times a year.