When she worked for a big computer company, my dw had a PDA (which I still read as "public display of affection" ;)). It was easier for her to carry than a big agenda book, and she could play games on it on the train, but I never had any desire for one. I watched her lose data repeatedly due to battery problems, software glitches, and damage to the machine itself. You can imagine my amusement when the Hipster PDA and Moleskine notebooks became all the rage in her field.
I feel rather the same way about the Kindle. From a publishing standpoint, I can see the appeal, but as a consumer, not so much. I'm sure it would be useful for certain types of reading - college textbooks, definitely - but it doesn't fit into my reading or buying patterns very well. Besides, I can't figure out most cell phones, let alone a digital book readers! ;)