You're right on these points. Mixi is basically the same from a functionality perspective, and what kind of activities they perform. However, there is a nuanced difference with the degree of sharing.
Also, Japanese who have been abroad defiantly do use it differently. One example is photos. I notice Japanese who have been abroad or have lots of foreign Facebook friends share far more photos than those who haven't.
Perhaps my article overplayed the professionalism of Japanese Facebook account. The accounts I've seen aren't on par with LinkedIn on their focus towards being professional. However, I get the feeling that Japanese Facebook users are much more conscious of what non-friends will think of their account than western users are.
I'll definitely agree about the photos -- Japanese people with foreign friends or who have been abroad are also much more aggressive with the photo tagging.
I wonder how much of that is just Facebook, though; when I started using Facebook heavily about a year ago after having an account since the beginning, I was completely lost about how to upload/tag/organize pictures. Facebook wasn't much help with its cluttered interface.
As far as self-consciousness, I don't think it's necessarily a Facebook thing... Mixi users are just as self-conscious and "groom" their profiles to be just-so -- the same for their profile pictures, which are their public face. I would argue that it's more a facet of Japanese society than of Facebook in particular.
I sort of think that the Japanese Facebook population of frequent users is still a bit too small to judge, too...
Edit: I meant to say this before, but mobage and gree are both much, much more popular with people under 18 than adults in my area. I wonder how much of that has to do with the commercials.
Edit 2: I just realized this, but I wonder how much of LinkedIn's lack of popularity has to do with the conservativeness of business culture in Japan in general. I mean, they have standardized forms for resumes and personal history here.
Also, Japanese who have been abroad defiantly do use it differently. One example is photos. I notice Japanese who have been abroad or have lots of foreign Facebook friends share far more photos than those who haven't.
Perhaps my article overplayed the professionalism of Japanese Facebook account. The accounts I've seen aren't on par with LinkedIn on their focus towards being professional. However, I get the feeling that Japanese Facebook users are much more conscious of what non-friends will think of their account than western users are.