This lore is pretty much the generic D&D version of the descent, with a twist on it. It's fine to me, and I also enjoy the new lore about the elves being able to change form in their original state. It is vaguely close to what I did in my own homebrew.
I don't mind at all the blessed elves/drow who can change sex (it's gonna be pretty fun in a Lolthite community), but I don't understand why such a blessing would come with the ability to only change sex, and not go back to a wider shapechanging set of abilities, closer to the elves of old (in their new version of this story). I mean, I can totally see why they did that from a real-world perspective, but it seems arbitrarily limited from an in-universe perspective.
Also, I'm so happy that the drow pantheon is back, and with more than a mere blurb in the book to just signal their presence. Eilistraee, Vhaeraun&Co will get their own section each this time around, according to what Crawford said here:
https://twitter.com/JeremyECrawford/status/973712612083945472 (the guy only asked about Eilistraee, Ghaundaur, and Vulkoor--from Eberron--but it's clear that all the drow gods will get their section). The elven gods being back to their normal selves (rather than "aspects" of the human ones) is also a very welcome addition.