I've just picked up a second hand Psion 5MX with the intention of using it to fit in the gap between when not at a desk/laptop and when in need of more than just a phone for jotting notes.
I've found the keyboard a little 'viscose' at first, but am slowly getting used to it. It's registering the spacebar hits that seems to be the most problematic so far. While I would be more comfortable at a laptop, the 25-40 hour battery life of the Psion and its complete lack of distractions might still win out in the end.
I've heard people claim to have written books and articles for publication on them. It is the distraction-free and long-life aspect I find interesting and am wondering whether to pursue writing on the device for those aspects in particular.
Do people write substantial works on electronic devices like these that are not laptops? If so, what factors are most important (either in the device or in how you use it), and what are the pitfalls to watch out for?
I have had time in the intervening days to type up some web content and book outlines on the device and so far it is fitting into the gap between phone notes (almost useless in comparison) and at-desk laptop sessions (with all the other distractions that entails) very well. I'd be keen to hear impressions of others who are straying away from their PCs to write
 i.e. of personal or professional importance
 Important in my case to avoid time spent typing up from paper.