It's a bad idea, and judging from a songwise great album I once owned (Anthem - No Smoke Without Fire), but the vocals with Japansese verses and English choruses annoyed me to the point that I stopped listening to it, and eventually got rid of it. It bugs me quite a bit because the music and artists preformances was great, but it can't be helped as the annoyance factor was tweaked to the max - IMO mixing up languages like that is the mother of all bad ideas.

Correct me if I'm wrong but didn't the Japansese band Concerto Moon do the same thing? I have never owned anything they've released - but heard a few songs here and there through the years