I am playing Xillia (as Jude) and really enjoying it a lot. I just obtained the fifth character and saw a couple skits with the fifth character.
I actually miss a lot of things from Graces f.
One, I miss things like the Discoveries. Something small, but it was always something nice to look out for and provided interesting variety and skits to the game.
Two, the mixing items together via dualizing. In older Tales games, you could create and/or mix items in some way depending on the game, like dualizing, cooking, or using a Rune Bottle, and I really enjoyed that. In this game, you get a lot of raw materials, but their only purpose is item donation.
Three, the titles. In older Tales games, you could equip titles, maybe for a small stat boost. In Graces f, there were tons of titles, titles you could individually level up and would provide benefits. In Graces f, the so-called "titles" are really just items in an achievement list. At least the achievements have a purpose - they give you grade (probably for New Game+ perks).
However, I do enjoy some things from Xillia. I like the Link system, for instance, and everything that comes along with it like the Linked Artes.