Bingo. Regardless of whether or not the online stuff is interesting (and it seems so), the offline game, which is both bizarrely short for a Level-5 game and ends in the most retarded way ever, is a grind. It's simply not fun by about the halfway point -- conveniently, the part where the story finally gets interesting -- and then the game goes right back to being a slog. The battle system, while initially seeming rather deep, never really grows after you spend about an hour with it. You can build in all these combos, but because enemies end up taking about three hits apiece and the whole Action Chip system is rather busted in that it takes ages to regain AC points. You end up either burning everything on low-level enemies to cut what is normally about a 15-20 second fight down to just a few seconds or you have all your characters blow their wad on bigger enemies because the tedium of transforming into a Knight and still thumping on everything slowly is just so goddamn boring.
There are also a lot of weird polish issues for a game that's so old. Characters skating around, clipping (one story character has a ponytail that clips through his cape all the time), boring music (the intro and ending songs are the only two memorable ones) and incredibly tiring battles mean that even though the game is "only" 30 or so hours long (a blink of the eye next to most Level-5 console outings), it still feels like it drags on too long.
The short version is that it's boring. Maybe the online with its voice chat and the ability to auto-run will help, but no matter how pretty and open the environments, having to fight the same color-swapped enemies over and over again is going to drag everything down, online or off. I've come to expect more from Level-5.