Hollywood Undead have a very unique type of music that is like a mix of alternate rock and rap. It is interesting and different and should be more widely known so the group can do better and so others can enjoy their awesome music like those of us who do know them do.
Hollywood Undead can hardly be called a niche act at this point. When even middle schoolers know the name of your band and everyone in it, you've reached the mainstream. As far as their musical talent and legacy goes, only time will tell. But I have a feeling their mixture of appearance and music will leave a lasting mark on this history of pop culture.