I pontificate in our print edition this month about what I see as a dawning of the age of the truly portable general-purpose computer (see here for an updated version with mutiple links). Shortly after writing the article I met someone taking an opposite view to my own, that ultra-mobiles will in the long term make dinosaurs (well... endangered species) of special-purpose handheld devices like the Ipod.

Anthony Sowden, of HP's Bristol Labs, heads a team investigating the design of the e-book, which he predicts confidently will be a standalone device rather than a feature of a general purpose machine.

It's an old debate: ten years ago people arguing for simple, narrow function devices were in the minority; today the Ipod seems to have conquered the world.

Sowden argues reasonably that ebook readers will want the kind of simplicity and ease of use of the Ipod. "They don't want anything that will interfere with their reading. You don't have to think about a book when you are reading. You don't worry about the paper or the typeface. You just want to read,' he said.

He also says that ultra-mobiles will need touch-screens which do not show text as clearly as a good straight TFT and are more expensive. But we can surely assume that screens will get better, though they could take decades or longer to come close to paper for reading or writing.

Sowden and I agree at least that the traditional book is not about to die.   But ebooks, whatever their physical form, clearly have advantages that make them better for some purposes and Sowden's team has produced an interesting design (top) that tries as far as possible to emulate how a paper book is used.

It weighs about the same as the lightest of the ultra-mobiles showed at Cebit but is thinner; pages are navigated by zoom buttons and four scroll pads on each side of the screen. This is optimised for easy reading and pages turn as quickly and as easily as a 'real' book - as the picture shows, you can even see them turn.

They also look far less scrappy than most web pages, and make you wonder whether ebooks may encourage a fashion for more traditional design.

The device has all the benefits, elegance and low cost of simplicity and would doubtless find a market at the right price.  But its minimal use of interactive features could irritate computer users who have come to take them for granted.

I am reminded of Palm, which scored a huge success with its early Pilot handhelds by designing them to do a very few, very useful, things very well. The company came unstuck when it tried to maintain that philosophy as hardware got more powerful and its rivals started packing in features, particularly wireless links.

The Kiss (Keep it simple, stupid) principle may work in politics, but in computing it risks insulting the intelligence, and needs, of users.