What I really want to see is what they've done with the stuff that was (still) useless in the WDex. Notably Repentia and the Penitent Engine, both of which don't seem to fill any role but that of expensive ablative armour for the rest of the army. I've yet to see either actually ACHIEVE something beyond attracting enemy fire.
... Other than one battle in 5th that had a Space Marine blow up a Rhino with Repentia in it with a close by Land Raider as his last action in his Shooting Phase - only to then realize what that meant
Ask not the Eldar a question, for they will give you three answers; all of which are true and horrifying to know.