Re: The first PDA
It was (and, to some extent, still is) far more than just a PDA. It was a full computing platform, and while people who haven't used them in earnest (I still have, and use, my MP2100) focus on the handwriting aspect*, there was far more to it than just that.
- No "filesystem", just a big "soup" of data. You don't need to worry about where their data is stored in some arbitrary hierarchy of devices and folders, or what you've called it, all you ned to know is what you're looking for. There's nothing quite like that, even now.
- Extreme integration. This lives on, to some extent, in some of Apple's software (for example, highlighting of (fuzzy) dates in Mail.app enabling you to add items to the calendar, etc, but Newton hooked into everything, even 3rd party apps.
- Write anywhere. The handwriting recognition might not have been perfect, but it fit perfectly with the form factor of the handheld Newtons. Keyboards worked too, of course, and would have been good for a "desktop" NewtonOS device. MS might be failing with their "one UI fits all" paradigm, but newton had it in the '90s.
- Expandability. USB, Wifi, Bluetooth, ATA storage cards, all aftermarket "hacks" for the Newton that work very nicely despite the fact they hadn't even been invented when it was released. Quite astounding when you realise the restrictions of the platform.
- Instant on. Really. Totally instant in most cases. Straight back to where you were when you turned it off. Even if that was weeks, months, or even years ago (in which case you might need to boot from cold, but you lose nothing - try taking the batteries out of your Palm pilot and see where that gets you)
What really killed it (apart from the price and the heckling) was the fact it was so radically different from other platforms. It was hard to make it work properly with the "status quo". Sure, you could sync it and keep your data safe, but that was about it. Interop with desktop apps other than calendars and address books was hard to do (and is even harder now).
Newton is probably the closest thing to the perfect computing platform ever invented (eclipsed, possibly, by the Lisp machines). It's a crying shame the rest of the world hasn't managed to catch up.
* The descendant of the Calligrapher cursive recogniser used by the later Newtons is now, I believe, owned by MS, which is why OSX's "ink" recogniser (OSX 10.2+) only handles printed handwriting.