Namco has been experimenting with bringing their "Tales" series into the online MMO realm in various ways for over a decade now in Japan, but none of those experiments have escaped to the West thus far save for this one. Granted, it's not strictly an MMO, as you can only play with four other people ad-hoc and the online component is limited to trading of items with other people from within the safe confines of your own little game world. But it's very MMO in its base structure, which is something like Phantasy Star Online but with the Tales battle engine hammered in.
The story is a fanfic-ish crossover deal that brings together characters from all the Tales games released up until 2006 or so. They all exist in this new world with their original personalities / abilities (and even their original voice acting for the most part), but the events of their individual games never happened. Instead, they're collectively part of a resistance to both an evil Galactus-like force called the Devourer that has thus far consumed 1/3 of the world, and the corrupt leader of the town in which you are based. The menu-based town serves as your initial hub, and there's two dungeon areas with multiple levels that you gradually work your way through in standard Diablo / MMO style.
Somehow, bringing down the evil leader and fighting the encroaching darkness both involve doing heaps of fetch quests for the local citizenry. 90% of the game is taking on quests from the lone guild in town that either involve finding X of some item or killing X of some monster in one of the dungeons. Once in a while there will be a plot-advancing quest you can select, which also sends you into the dungeons but usually has some cut-scene story elements and winds up with you fighting a boss of some sort.
Eventually, the game lets you move on to a few other towns that each have their own dungeons nearby, but the core process of taking on fetch quests to build your character up to take on the more difficult story-advancing quests never changes. In addition to basic leveling-up, you gradually learn new crafting skills that let you make more potent items and equippables from materials you get from battle drops and from mining certain spots in the dungeons. You play a custom character who can switch between character classes (drawn from the various other Tales games), and your appearance changes with each new armor/weapon/accessory you equip.
You can also recruit the other Tales characters who are hanging about in town to be in your party temporarily. There's a reputation system that's supposed to complicate this, but it's really simplistic -- at first most of them will join you, but some won't, then you do a few quests to boost your rep and suddenly all of them will join you. Sometimes a quest will automatically place one character in your party as well. In all cases, they only stay with you for the current quest, then automatically bail when it is completed or you cancel it. You can't mess with their equipment, but they do level up while under your care and you can give them battle instructions.
Since you roll a custom character and the game voice-acts the dialogue, your character is mute and you get saddled with the stereotypical wisecracking flying cat-ish sidekick who talks for you. More of the entertainment value here is going to be for longtime Tales fans in seeing characters from different games interact with each other complete with voice acting, which can sometimes be legitimately pretty funny.
Unfortunately, the core gameplay is pretty tedious. The iteration of the action-oriented Tales battle engine is solid, but quests involve too much repetitious trudging of the same dungeon floors fighting the same endlessly respawning enemy mobs over and over. You're given some leeway to run around enemies, but they respawn mere seconds after defeat, so having to double back sometimes turns into a gauntlet of repetitive battles and this gets worse with the faster enemies on deeper levels of the dungeons. Enemies never lose their aggro hard-on for you even when you're miles above them in levels, and you have to start each dungeon from level 1 each time you enter, meaning a chain of pointless battles accompanies pretty much every single quest.
Namco obviously sunk money and time into this game, treating it as a viable branch of the franchise rather than just a quick MMO spinoff to take advantage of market trends. The characters and dungeons look nice, backgrounds are polished (though there are relatively few of them), there's extensive voice acting, the soundtrack is OK (though not by Motoi Sakuraba), from a production perspective there's really not much to complain about. But the repetitive fetch-quest PSO-style nature is beyond outdated at this point, and even though the battle engine is better than what most MMOs offer, I still don't think anyone will really get into this unless they're already a big Tales fan who wants another outing with their favorite characters. As an actual massive MMO this might have worked better, but as a mostly single-player experience it's lacking.