For me it is hard to specify things about a particular Nirvana song versus all Nirvana songs. A big part of them are Kurt Cobain’s voice which is beautiful in its rough quality.
I love the contrast in this song that goes from a slow quiet sound to loud fast sound. It really shows the kind of messed up nature of the emotions the song is portraying. Lithum is a common treatment for bipolar disorder after all.
Maybe its because I grew up in the grunge age but these sounds always seem so full of aggression and feeling. It could be it touches me a little more because I liked it when I was in my “formative” years.