The MessagePad 2100 and more than likely by extension the 2000 is an awe-inspiring piece of equipment. Featuring a removable over-the-side screen cover, a flipout stylus holder, a pretty loud speaker, a microphone, two PC card slots, NOS 2.1, more compact battery packs and a new and useless Interconnect Port, let alone the larger, sharper backlit screen (to activate, hold down the power switch for five seconds), this Newton is a force to be reckoned with.
The stylus holder is very cool: if you push up the small bit in the top-left, it extends nicely to act as an inkwell type device. If you use the device in landscape mode, it sits at either the top-right or bottom-left, making it nice and easy to grab on your way to writing.
The microphone and speaker are a nice touch. The rumor was that the 2100 was designed exclusively as a speech recognition platform. I read once that there is a demo of the Dragon speech recognition engine that you can grab, but I wouldn't know where. Try the UNNA first. The built-in feature is that you can record sound at 2K, 4K or 5K a second for something like an hour on the built-in memory, much more if you use a flash card. It eats up a bit of the processor and handwriting recognition seems to suffer for it. But if you can remember to write clearly and not scribble, it is an amazing feature that I hope to use during class one day if my teachers will allow me to use it as a note-taking device.
The Interconnect Port is useless. The only peripheral for it is a serial adapter. Mine came with the PC version of the cable, so I'm out of luck there. I have to use infra-red to move raw packages and I'm having trouble with my wireless network's encryption. (Anybody with Verizon FiOS that got it down, please let me know what I'm doing wrong.)
The battery packs are a nuisance at the moment. I have two of them. One runs for 19 minutes before dying, the other is rebuilt--well, no: reanimated is more like it--with regular Rayovac NiMH AA cells. Even though they only output 1.2V, they seemed to work in my 110's battery pack (basically a steel label over AAs) just fine. Right now, it usually doesn't work, though it did turn itself on at 11:30 last night for no reason. I promptly disassembled the battery for further experimentation. Rewiring some questionable contacts remains inconclusive. Aluminum foil seems just as reliable as copper wire and electrical tape. My advice: be patient and order AAs WITH SOLDER TABS off the internet. I think I permanantly damaged the cells. It was simple to rewire, except that the thermistor had to go. I think I fried it.
The device itself isn't as attractive as the 110, 120 or 130 in my opinion, though is far from ugly. That said, my rubberized paint is flaking off all over. I need a new faceplate and/or a repaint. I'm thinking a very dark blue would be nice. Anyway, this thing is enormous compared to the 110, though it feels much lighter. I don't know if that is simply my perception of the leverage generated by its wider dimensions, though.
As for software, see my Newton OS page. This runs NOS 2.1, a very nice piece of software that is way ahead of its time.