Yeah, I've tried the BC case cleaner on several occasions.
It seems to be some kind of mild organic acid cleaner and DOES clean and brighten the brass on first and second use, but loses its effectiveness quickly.
I could not identify it from it's mild odor (that's why I think it's an organic acid), but neither is it harsh on hands or skin. No special handling precautions except eye splash protection.
I don't think it's cost effective for only one or two uses though.