That was always the biggest sourspot for me when I had Vesperia on 360.
Flynn is ON the boxart...why was he there?! Tradition has playable characters on the boxart of Tales games. Front and centre.
For those who are aware Flynn shows up throughout the game as a tease. Story reasons prevent him from joining you but as it progresses it seems he might actually say "eff it" and do it anyway as the world crumbles around him (like any RPG plot). He's friends with the main character after all, right?
So finally, VERY late game he suddenly joins your party! YES! I think! How perfect! A late game party member! How uncommon! That's so cool!
...wait, what do you mean "Flynn has left the party", game? That was just one simple battle and he's gone. He's...only playable for one fight and that's it?
(Yup, that was really it for the Western versions. One single footnote of a battle and that's it. And then the super-chocolatey-fudge-mega-superawesome-JP-only version comes out with everything you wanted and more...as was ALSO tradition by this point. And I got very sad. :< )
...Eh whatever. It's an excellent game. It's up there with Symphonia in terms of great Tales games imo.