I don't listen to Justin beiber, but I'm pretty sure his squawking isn't opera style. At least, if that's what the kids are listening to today, I'm more out of touch than I thought.

I thought the music in the dungeon was pretty fitting. Something haunting that will kill you if you find it's source. What type of music do you think that a Siren would sing? Only other style I can think of is what they used in "Oh Brother, Whereart thou". As for the fight being disappointing, I think a lot of people are just sad that fights like Siren, Diablos, and Fenrir are in game and they aren't anything SUPER special. I love seeing those bosses, but of course I want more.

Now several of the fights themes in this game are really cool until they switch into fairly generic J-Rock. I typically enjoy the first half of dungeon and boss music more.