I use my Palm TX all the time for reading books and watching movies and do so because it's small enough to carry everywhere and powerful enough to show full-screen video at full frame rates.
It's useless for note taking thanks to the abomination known as Graffiti 2 (thanks a whole lot Palm) but still functions as an appointment reminder.
So what about the Kindle? It's big. I couldn't put it in a pocket. On the other hand it does one thing and some think it does that one thing quite well.
What's your opinion?