So I bit the bullet on Ragnarok Odyssey Ace (Vita version). I'm enjoying it so far, although I'm too early in to try out the extra content.
Here's some changes I noticed:
Visuals
-Everything looks sharper and more colorful somehow. I have no idea why. I did notice that several shops have more details added to them.
-The game still runs at native res, 30fps in single player.
-Lots of small cosmetic changes to the attacks of certain classes.
Story/Presentation
-I don't think the vanilla version did this, but Ace gives you tutorials on everything. Card equipping, expanding, refining, the works. They also give you tips on the loading screens.
Gameplay
-Four types of control schemes. Two use the standard triangle/circle for attacking while the other two use square/triangle.
-Potions can only be used with the touch screen. No idea what Select does now.
-Classes can no longer charge their heavy attacks. The first ACE skill you receive basically replaces that function (with minor differences, e.g. the Sword Warrior's Magnum Break skill will launch enemies as opposed to sending them across the room, and only seems to have one charge level).
-ACE skills can be triggered using the touch screen or pressing L and square/triangle/circle/x at the same time.
-Hunters seem to do more damage from longer ranges (I can be farther away without seeing '1's constantly popping up with each shot.
-None of the classes seem to have new moves outside of their ACE skills.
As I get farther, I'll hopefully get more ACE skills to mix things up a bit. I've been reading that the drop rates are lower in this, so maybe I'll finally be able to get an epic-tier weapon in this.
EDIT: Megaton. You can contact the Blacksmith and Clothing shops while in the Tavern.