I played the first game recently. Not much though. It's pretty cool. Timed hits in combat, that's good. The first dungeon is really really bland though. Does it get better?
Honestly...no.
[spoiler=reveals the plot behind the game]As you play, you'll notice a particular kind of enemy appearing called Einst which are incredibly tough for the dungeon you'll be in at the time. Apparently THEY'RE the entire reason why the world's are so [tornado fang]'d up and all this is mentioned literally right before the final dungeon, which effectively is nothing more than a 3-4 boss Rush Mode of particular bosses, and when you beat the game, you find out that all the worlds used to be one until someone went and [tornado fang]'d it all up (I don't know who since the only Einst you actually meet says he wanted to fix things, albeit in monotone zombie speak, but apparently the crystals that are associated with them are also making a giant mess). Haken also apparently is some kind of prototype and the Black Phantom is his Personal Trooper who somehow manages to get the other two PT's to join the party (the third one just explodes), but overall they impact the story of the game with minimal effect.[/spoiler]
The combat also gets old since you stop getting new combat skills shortly after level 20 or 30, and as for a New Game+, all you get to do is keep items that aren't important. Your levels, skills, and stats disappear back to the original values. You don't unlock any new side quests or missions, and as far as hidden things go, it seem as if only the hidden boss fight (which is actually a joke depending on your levels and items; if you can beat the final boss, you can beat the hidden boss and vice versa, there's almost no difference stat wise) is the only thing there. Once you beat the game, there's almost no reason to go back in playing it unless you just want to wail on the enemies with the weapons and armor you had beforehand, and I'm not sure if you can stock up on the weapon the hidden boss gives you.