Let me get this out of the way first: I love the Tales series. Not all of it, but most of it. I consider Vesperia, Symphonia, and Abyss to be the holy trinity of the Tales franchise. I personally enjoyed Symphonia: Dawn of the New World more than most people did. I am not a fan of Legendia, and Graces f was kind of "meh" for me. Xillia lies kind of in the "meh" category as well.
For the first time in the Tales franchise, you're able to choose between two protagonists: Milla and Jude. Jude is your stereotypical JRPG "nice guy" protagonist who's always going on about friendship and saving the world. Milla is a borderline emotionless woman who doesn't have much in the way of a personality. Pick your poison. Depending on whom you choose, some events are told from a different perspective. This does add some replayability, but if you don't enjoy the game on your first playthrough, you're not going to want to play it again.
The story starts off with some intriguing plot points, but soon loses its steam. There are a few plot twists here and there, and the story is appropriately large in scope, but the problem is, the plot twists just lead the story in an odd direction. What makes it even worse is that the last ten or so hours of the game are completely rushed and feel incredibly choppy. To make it even WORSE, the game is about ten hours shorter than your average Tales game and can be beaten in roughly 30 hours. Of course, if you take upon side quests, you can spend a lot of time with the game, but the main story is surprisingly short.
The characters don't do much to help the story. As I already mentioned, the protagonists are bland. The only interesting character in the whole cast is Alvin, but I can't guarantee you'll like him. The rest of the characters are more or less walking cliches, which is especially disappointing for a franchise that has so many amazing characters.
The visuals of this game are nice, but they do look a little dated. I can't fault the game too much for that, though, seeing how it was made a few years ago. Environments look nice, and the character designs all look good. There's also a third-person camera, which is new to the Tales franchise, and it works decently well.
The soundtrack is fairly good as well. There aren't a lot of memorable tracks, but there's nothing inherently offensive or bad about the soundtrack, so it's hard to complain.
If there's one thing I won't fault the game for, it's its battle system. Battles are fast and fun, and there are some interesting features that make battles more interesting. This definitely keeps things interesting during the monotonous traversing.
The traversing the world is monotonous due to the uninteresting locales and environments. Exploration is incredibly restrictive, and the game is almost completely linear. Dungeons aren't especially interesting either, and some of them become incredibly tedious to go through due to their awkward design.
Did I enjoy my time with Tales of Xillia? Eh, sort of. Battles are what made the experience tolerable for me. The world is uninteresting to traverse, the story falls apart really quickly, and the characters are boring. I really wanted to like this game after my disappointment with Graces f, but this game is actually worse. I have a hard time recommending it. If you're a Tales fan, go for it. A lot of people seem to enjoy it, but I personally didn't.