sonicstar4453 and shroober99, both of you are wrong. The name of the music track that you two are thinking of is "World of Nothing".
This is actually a remix of the music that plays in Castle Bleck when you temporarily play as Princess Peach after you've beaten Chapter 1 and got the second Pure Heart, and it is also the same music that plays in Castle Bleck when you temporarily play as Luigi after you've beaten Chapter 2 and gotten the Third Pure Heart.
Now that we've got that confusion out of the way, it's time to analyze this particular remix of that music.
This version of Into the Darkness is darker and more sinister sounding than the original, giving an even more creepy atmosphere to an already creepy theme.
I liked the instrument choice, it really set the scene as if something really bad was about to happen.
Truly an amazing rendition for one of most unsettling tracks from the darkest Mario game of all time.
5/5 stars.