A Japanese survey of mobile phone users, translated by What Japan Thinks, reports that only about 10% of Japanese mobile phone users say they have mastery (or a good command) over all the functions of their mobile phones (link). About 75% of users say they have mastered less than half of the functions in the phone.
The most confusing functions were e-wallet, applications in general, music player, and Internet access.
What Japan Thinks concludes that few people in Japan "are really comfortable with their phones," which I find reassuring because it says that people in Japan aren't all that different from everyone else on the planet. In many countries there's a tendency to believe that people in Japan (and Korea) use mobile devices so differently from everyone else that there's nothing useful to learn from them. It's as if they're on a different planet. But the reality is that even in Japan, a phone overloaded with features and cryptic menus is confusing to anyone except the most dedicated technophiles.
It is interesting that so many mobile phones in Japan have e-wallet, applications, music, and Internet built in. That's a result of the aggressive rollout of integrated phones and online services by Japanese mobile phone operators -- the real driver that I think makes the Japanese mobile market so different.
(By the way, in case anyone's interested, another survey determined that 14 percent of Japanese cats won't go to the bathroom if someone's watching [link]. Who knew?)