I'm loving the Nether update so far. The Nether has become a place I'm excited to explore and interact with, rather than just a place I use for fast travel and blazes/wither skellys. The new music is one of my favourite parts; it does't really sound like anything done in the past for Minecraft, but that's okay. It gives the Nether and the biomes a lot of personality. I really, really like the idea of biome specific music and hope it sticks around for more.
I'm thinking they could do something to make the two new forests stand out more. I understand there are differences, like Enderman in the Warped and the Piglins in the Crimson, but for the most part they seem like a red and blue hell forest. I like them both a lot, though. Maybe add a unique structure to each?