I'm a huge fan of the Apple Newton, and I've written about it several times here at TUAW. I've also spent time playing with a hipster PDA and the D*I*Y templates.
Today I noticed a bit of convergence as dougj at D*I*Y Planner has picked up a Newton 2100 of his own, and is loving it.
I won't go into all of the great Newt functionality that I enjoy in this post (look here for some of that), but I do agree with dougj when he says, "The address book and calendar/to-do lists are more than adequate...and the Assistant that correctly interprets 'Remind me to take out the garbage' or 'Lunch with Mary at the club' allows me to manage my time and tasks no matter where I am in any program."
Welcome to the club, dougj! I'm sure you'll enjoy your stay.