Not really
I've owned a PDA since the Palm 1000, and about half a dozen since then. I always have it out and ready during meetings, classes, etc.
In theory, it should be perfect for my note-taking needs. I don't draw diagrams or even arrows when I take notes; they're pure text.
But it never quite seems to suit my needs. It's just too slow. I've tried both Graffiti and Jot, as well as a "retrainable" version of Graffiti. Both too messy and slow. I've tried various alternate tap keyboards like
MessagEase and
Fitaly. I've tried word-completion dictionaries.
All had their advantages, but none really helped me enough to make the transition. I got pretty fast at Fitaly (they include a training tool, "Letris", that's pretty addictive), but it still takes a lot more *thinking* than handwriting, and I had trouble taking notes and listening at the same time.
None of the handwriting-recognition programs can recognize my handwriting, which isn't really their fault, because I can't recognize it either.
YMMV, especially now with thumb keyboards widely available. I haven't used one yet, but my next cell phone will be a PPC with a slide-out keyboard.