So now the FAQ and Ynnari Index has dropped you can see what has changed etc.
Biggest changes to Eldar is the inability to use Drukhari and harlequin units to take advantage of the Jinx and Doom powers. This makes skyweavers and disintegrator ravagers a little less potent (but still good). Flyers not blocking movement is also a big deal for Eldar.
As for Ynnari, totally changed and I'm still wrapping my head around some of the options.
One thing that did't change is -1 to hit traits which means Alaitoc still is the defacto choice for Eldar,which bugs me.