I feel the same. I loved my IIIxe. I'm guessing we'd be horrified at the UX now if we could go back, but at the time it was a huge boost in productivity. The handwriting language was really great. I actually wrote papers on that thing! It was great, I could work on papers while on the bus or travelling, without having to lug around a laptop. Remarkable devices.
I played with an emulator (https://cloudpilot-emu.github.io/) recently and it's honestly not that bad at all. The resolution is bad by today's standards but the basics are all there. It even has a system-wide search that looks for the input string in all your apps and lets you tap right into those records. That's pretty handy!
I like my phone too much to go back, but if I had to, I could make do.
