I had a Psion 5, an amazing device. It had the same apps as the 3, if I remember correctly. The keyboard was astoundingly good. The keys, if larger, would make an excellent normal keyboard.
What I really loved about the 5 was that it could run Java. I think it never got past JDK 1.0.2, or maybe 1.1. But it was clunky to use. I wrote a little shell for it, which provided basic functionality, including much simpler compiling and execution of java code. (http://geophile.com/jshell. It should still run, except that it relies on an obsolete parser.)
Um. Well, yes, broadly, true, but then they are largely similar across most PDA type devices. Address book or more general database, calendar/agenda/scheduler, notepad or jotter, maybe a file manager, then often some kind of minimal office-productivity tools or viewers...
What I really loved about the 5 was that it could run Java. I think it never got past JDK 1.0.2, or maybe 1.1. But it was clunky to use. I wrote a little shell for it, which provided basic functionality, including much simpler compiling and execution of java code. (http://geophile.com/jshell. It should still run, except that it relies on an obsolete parser.)