Ok so. At the risk of typing up a storm like I have in some of my other posts (check my comment history for some super long opinions of Xillia 2), I'd like to make this one short enough to capture the flaws but still say that I thought the overall game was good.
For the most part, the game world is the exact same. Nearly every single Xillia 1 asset was reused. It's not an exaggeration. They WERE all reused. There are a very select few new areas, but there is definitely no sense of world exploration. The idea is that the game is taking place 1-2 years (can't remember) into the future, where both Rieze Maxia and Elympios have developed and gotten to know each other. That's not to say they're best friends (in fact, the game tries to explore the rivaling tensions between the two, even though that's barely developed), but is to say you're exploring an already existing world. For that reason, the few new areas you explore don't have that feeling of "Woah that's so cool I've never seen this before".
As for the Xillia 1 characters, they suffer from the same problem as the environments. They're already developed, so it's hard to do anything new with them. However, and I know I'm not alone in this, Xillia 2 seems to suffer from a profound sense of isolation. This is because the characters barely feel like they interact with each other. Now, there are special character side quests throughout the game designed to give the original cast some more spotlight time that you pretty much have to do or you're not really playing the game (you will really be wondering what the hell the original cast is doing throughout the main story), but the problem with the quests is that it really only ever focuses on two characters at a time. Those characters are (usually) well developed over their questline, but they're so isolated from all the other characters that you really only ever feel like an escort for the miniadventure of two characters. The heart of the problem likely lies with the fact that there's a huge cast (9 playable characters, plus Elle) and so it's difficult to capture all their quirks in a single conversation, but there's a bigger issue in that the game is divided up by missions.
Remember how in literally every other game, when you were on your way to some grand destination, the characters would have cutscenes to make dinner and make fun of each other, or entering a new zone would trigger skits? Well Xillia 2 fills the void with the hunting board, and instances off the actual quest line. Therefore, there's never a time where you first arrive at a town or something, and some character says "Oh yeah! This is my hometown!" and some character replies "Oh no! Is everyone else here as insane as you are?" It's just silent farming. It really feels like you're playing an already beaten game, and are just exploring already explored territory, without triggering any events.
And speaking of silent. Ludger is literally a complete self-insert of a character. He says nothing apart from one word answers (Yeah! What!? Uhh...) or laughs. His actual dialogue is one sentence responses to the actual characters driving the story, and almost makes you wonder why he was even included, other than to go super saiyan in combat.
As an asside before I forget, the combat is pretty perfect. 0 complaints, really like the dual mystic artes and how you could make your partner use their mystic without actual playing as them. Chromatus mode is also super cool. Nothing really new to add, just that combat is fun.
Ludger's lines aren't even voiced unless you beat the game once and unlock his voice through the grade shop. Seriously. His VOICED OUT LINES ALREADY EXIST.