I beat the shit out of the original game, got all my characters to 70 with sick builds and beat the optional boss. I made it to the golden giant or whoever that boss is in the sequel, it's a really tough fight since only my gunner can deal good elemental damage. I got close to beating him but put the game down and haven't picked it up since, I'm really close to the end so I should probably follow it through.
It's a really great game series, I don't expect a lot of people to like it but there's a lot of strategy involved and always a sense of urgency that's missing from most RPGs these days. The only thing I'm not sold on is that a lot of the boss battles have luck involved, hoping they don't spam their most powerful attacks.