Hauntingly Fabulous.
I love their styling, very real-world suave. My one issue with it is that even though they all look awesome, they also all look very similar so it's hard to drag new people into the fandom on a bias-basis, or to help new people figure out who's who. They're also not put individually on sets that stand out dramatically from each other, though to some degree, the continuity aspect of the MV is thematically fabulous. All of the ZE:A boys are the narrator, the every-man that she can't see in the lyrics. Also the choreography has them in a two-tiered line for a lot of it, so you can't even just say 'the one in front right now is Hyungshik'. Other than that the choreography is pretty cool, the MV doesn't capture all of it's awesomeness though. I suppose there's something to be said for saving the best moves for the Lives, but the MV doesn't feel nearly as grand as the Live performances look. Sure, there's a few good moves in the MV, but the Live choreo is phenomenal.
Song-wise, it's fabulous. The use of the accordion was unusual enough, but they decided to take it to an entirely different level with the throw at Gregorian Chant sounds. They really took me by surprise, and yet they work perfectly with the established sound (though honestly Gregorian Chants are epic enough to work with anything). Also, the long white costumes make a throw to the time period Gregorian Chants originate from, so bonus points for continuity. The string sounds littered throughout the piece give it a fabulous vibrancy, lifting the main line up to settle smoothely in the boys' upper ranges (which makes the deeper chant sections stand out all the more). Between the strings and vocal lines, the song is incredibly active. The bridge isn't spectacular, it seems to really just be stuck in there because songs need to have bridges; the chants should have been more a feature of focus, the beat should have dropped out, one high voice should have risen dramatically above it all . . . as it is, it's still nice, but not incredible. But it's catchy and I love it.