To a certain extent I agree with the others ... in asmuch as currently to get the best I need RISC OS and Windows (or Linux or MacOS).
For some work RISC OS is simply better and faster; just take the short time span between getting home from work and supper - enough to fire up my IYONIX, read my mail, reply to the odd one etc. With my Windows system (a reasonably fast one with 2.4GHz Core2Duo, 2GB RAM, WinXP) time would be tight since it is still booting while I read and reply to the first mail and usually when I would manage to have launched the email program and polled mail I'm done with email on my IYONIX. For DTP, Graphics and some other work the IYONIX pc is faster and less sluggy too. For some tasks Windows wins though - be it the much better spell and grammar checkers (I prefer a German one at that) or a good browser or online banking apps or video work. (I use Windows and not MacOS or Linux simply since some apps I really want to use run on Windows only, otherwise I'd be open for the other two.)
For a small device to be considered with RISC OS to start with the main app missing is a browser you can really use - despite all progress of NetSurf and Phoenix both are way behind and the FF2 port of Chocky is useless (too long load time, much too slow, ...). Furthermore such a small device needs good connectivity - WLAN with up to date encryption to start with.
True, as an OS RISC OS would probably be a very good choice for the small ARM powered gadgets, especially since it is an OS natively made for ARM and for use in ROM and not ported and thus probably more efficient. But as Jaffa and hEgelia outlined: The time when it was enough that the gadgets work nicely is past - they have to do a job and the apps needed for that are still amiss. But if someone would write just those missing apps, well then the RISC OS desktop computers would benefit too.