I haven't seen Dances with Wolves, but even if I had, I doubt I'd have liked it as much as Last Samurai. Being a Japanese Studies major, I'm just more prone to finding things about contemporary Japanese culture (this isn't quite contemporary, but close, since the Meiji Restoration was the beginning of mass modernization in Japan) interesting.
Personally, I liked the film quite a bit. It doesn't matter to me that other films have taken the same angle...while the specifics are endlessly variable, as far as themes go, there are only so many; it's not how original a theme is, but how well it's done. And The Last Samurai protrayed it's theme exceptionally well, in terms of music, scenery, acting, etc. I found that the film was great at expressing "aware" (pronounced "ah-wah-ray"), which is the concept of longing, one that pervades Japanese art. Admittedly though, sometimes the movie went too far, moving into outright angst - I think that this is because American cinema tries a bit too hard to evoke emotion in its audience (as a generality); "aware" is quiet longing, but at several points the movie was trying to portray a much deeper sense of loss.
It was also interesting to view the movie against its historical context. The
Satsuma Rebellion wasn't nearly as cut-and-dried as they portrayed it. As it actually happened, the Rebellion was based on political reasons; not cultural ones.