The cutscene with the former Archduke of Juno (don't get me to remember his name, please) implies he's scheming something, but I doubt much will come of it.
That said, the update has gotten pretty fun. New Icons unlock if you clear Missions, new stages, and new music that unlocks when you clear all sections of a mission.
The Missions themselves reacquaint players with mechanics that they may or may not be familiar with, helping them increase their basic knowledge of the game. I recommend taking on missions in Sparring Mode at first.
Set it up like this:
(3 ally team vs 3 enemy team all stationary) and you can practice locking on to enemies, dashing, jumping, and move cancels.
For more advanced missions I recommend using an Assassin type like Noctis or Kain to practice the cancels.
For Recoveries/Blocking/Evading there's another good setup to play with:
Have Terra equipped with Riot Blade HP attack (she'll almost never use it) and set her at the highest difficulty (Crystal if you have it). That way you can spend time dodging her spells, hitting her when she evades around, recovering from hits/breaks and wall splats.
Alternately fight against Cloud with his Cherry Blossom equipped for a better chance at getting smacked to the ground/walls of a smaller stage.
Once you clear these missions you get Gil (for buying the new songs) new icons for avatars, and new music (some of which is pretty obscure tunes from every FF game which is really nice).