Miku will help sell pretty much anything, she's huge in Japan. I'd say that the games don't get localised because all of the songs are in Japanese, so there's no point. That hasn't stopped me playing them though, they're actually pretty good. I even have the second PS3 one. There's an English version of the Miku vocaloid on the way, but I have a feeling that it won't change much, unless it really speaks English well.