Menus and software open noticably faster. Click-on modem feels more secure. To big, about the size of the newer color PPC coming out, but the casio was tiny compared to the Nino. Still fits in a shirt pocket, but more awkward. No head phone jack, although Casio jack was mono and should have been stereo in the first place.
Screen is more difficult to read with backlighting off.
Thanks to the NiMH rechargable, you can leave backlighting on all the time. Buttons on the side are accidentally activated much more often then the recessed button on the front of the Casio. I still plan on getting a color PPC, but not the HP 420. The Compaq and Casio are delayed again, so we'll have to wait. Overall, I would recommend the Nino 320 highly.