The Tales series is sort of like the most film series where the formula changes only ever so slightly in every iteration and remains comfortingly familiar. In a nutshell, if you've ever played any Tales game before,you'll know how to play Tales of Xillia since the only new things they added seem to be linked artes.
Even the storyline is extremely familiar. There's a guy (or girl depending on who you choose) that suddenly gets caught in a series of unfortunate events, that lead to kingdoms declaring war on each other. Along the way, he picks up a rag-tag band of misfits, including the sex symbol, the older wise guy, the male sex symbol, the moe girl and the childhood friend. It's pretty average though there are some pretty WTF moments in it.
The game constantly espouses the fact that spirits and humans are supposed to get along together and how spirits are sentient and have their own lifes as well and how killing them is wrong but then at the later part of the game, Milla; Lord of Spirits, basically states that "Ok, humans killing spirits is bad. But you know what, I'll make sure that in order for a certain subset of humanity to survive with all their modern amenities intact, I will make sure that for every spirit they kill, I will keep creating spirits so that the balance is kept in check". At which point, how are spirits different from chickens again? It's not even like most of the humans would die without their electric (spirit-powered) lights or modern plumbing or such. Granted, a small portion would actually die because they have pacemakers or such that rely on killing spirits, but again, you're basically sacrificing one sentient race for another without the consent of the sentient race being sacrificed. Wtf is this message?
The real drag on Tales of Xillia though are the characters. The problem really is that most of the cast of ToX are either very bland or basically people you love to hate. Case in point, Jude; one of the main protags, is extremely extremely bland. His ONE characterisation moment also makes him out to be a bit of an ass. Then there's Alvin, who is basically a revolving door of backstabbing treachery. He even gets CALLED on it in the story, yet somehow he always manages to come back without any retribution. Seriously, wtf. Then there's old dude, who's basically stereotypical wise old dude; who may or may not be gay. Milla who's emotionless sex symbol, the rori who's basically one of the more awesome characters in the story but only because she gets partnered with Teepo (yes, I like Teepo)
And then there's Leia, who's basically the most awesome character in the game. Mostly because she's fun-loving, thoughtful and kick-ass. Yet, she gets relegated to one-sided love interest to her childhood friend, who's obviously too dumb to see how awesome she is.
The game is also just a bit easier than I expected from a Tales game plus the ending really goes nowhere. It just comes out of the blue, in a dungeon that's almost pretty much straight forwardly linear.
Overall, I'd say this is maybe one of my least favourite Tales games. I would definitely rate it below Tales of Vesperia *currently no.1*, Tales of Abyss and EVEN Tales of Symphonia.