This reminds me of that BoLS 'article' that went up today: unnecessarily negative and honestly pretty annoying.
It's genuinely awful.
Exarch powers don't make any sense, they should benefit the unit, and most of them are awful anyway.
Warlocks can't determine their powers before they get split off to units.
Wraith Lords are far too expensive now.
The fliers are made of paper, for their cost they die far too easily.
Scorpions are pretty much unusable now, the Mandiblasters change neutered them pretty harshly.
The Psychic Powers are mostly garbage, and the lack of reliability is extremely un-Eldar; they should be able to re-roll their power rolls, or at least Farseers should.
Starcannon are still terrible and overpriced (except on a few things, but they're still bad overall).
The Wraithknight's weapon options are awful, the sword is worth LESS than his standard weapons by far, and the Suncannon is ludicrously expensive. It can't even fire more than two weapons (meaning you can't take advantage of the Scatter Laser's great ability properly).
Fire Dragons are far more expensive than they should be.
There's basically no point in taking the Warp Spider Exarch, since his powers are all terrible and massively overpriced (TWIN LINKED GUN ON A BS5 MODEL, REALLY?), and you don't really gain a damn thing from him being there.
Most of the Phoenix Lords are just plain bad, and don't do what they should, which is modify the FOC to favour their aspect and provide buffs to the unit they join (like all Exarchs should do).
Yriel is a shadow of his former self.
Eldrad is way too expensive for how massively gimped he is.
They now have basically no Psychic defenses, which makes absolutely no sense.
Runes of Warding and Witnessing are nothing like what they ought to be.
The person who authored this codex should be ashamed, they have absolutely no goddamn idea what the Eldar are all about, and have written a horribly underpowered waste of money.
This book is practically unusable in competitive play, there's a lot of good changes (battle whatever and shuriken weapons being two of them), but almost everything else has been made absolutely awful.
It's offensive, they've shown an absolute lack of respect and understanding of one of the most interesting and important 40k races, and the entire codex needs to be re-written by someone who actually knows how Eldar should work.