And... that was it. New NPCs offered a glimpse of some truly amazing armor and weapons, none of which are currently available to players (and datamining suggests it may be a while, if ever, before they are.) There were no new appearances for players to farm, no items or pets or toys or titles to obtain, no achievements to complete. There was no repeatable, truly farmable content.
Void elf - "Many have sought to harness the corruptive magic of the Void. Most who tried have fallen into madness. Determined to use this power for the good of Azeroth, Alleria Windrunner is the first mortal to succeed at defying the shadow's whispers. Coming to the aid of a group of her kin who nearly gave in to the darkness, Alleria has vowed to train these Void Elves to control the shadows within them and pledge their newfound powers to the Alliance."