What prejudices are you talking about?
Well, I found this thread just after seeing the movie and replied instantly without thinking to much
The name of the thread and replies seemed not righteous for me at that time. Also this thread started way before the movie was produced so it looked to me that there were some prejudices, and I am a bit sensitive to that lately. For instance, after seeing this movie I do not think Keanu Reeves raped Japanese culture. But then again as an European in the 21st century I do not know much about the culture so maybe that's why I didn't understand it.
First I must admit I do not know the story of the 47 ronin exactly as it been told originally (I doubt there's only one version) but in my opinion the producer and Keanu did a good job in making a convincing movie about it. Despite the fact that Keanu is a bit wooden/stiff/clumsy, I didn't noticed it much in this performance. Minimal facial expression suited his role of lowest class/bashed/outcasted 'demon'. In fact in his role he wasn't a Samurai but followed the 'bushido' path more then the Samurai were. Also the mythical and alien looking creatures in the movie didn't bother me because I have seen (read) those in Japanese saga before. All in all a nice and beautiful American style movie about the Japanese story about the 47 ronin, surely not for everyone.