Great RPG!! Underappreciated!!
There's a lot to say, so I'll focus only on what i consider the basic stuff of the game.
BKO take place 20 years before the first BK, also this time u r a guardian spirit from another dimension, but now u r bounded to Sagi, a spiriter that joins the Dark Services (some sort of elite military unit) of the Alfard Empire, his first mission is to kill non other than the Emperor itself. =O Starting there, eventually the story explains the universe of BK, floating continents, why people have wings, the evil god Malpercio and the particular story of characters from the first game: Geldoblame, Gibari and King Ladekahn (LOL!!), Giacomo, Savyna, Dr. Georg, Lord Rodolfo, and others.
About the battle system, I wouldnt say it was "improved", but simply changed from the first BK, though actually there were some improvements, like predetermined decks, I mean, u can form different decks and then u just pick the one u need according to the situation; environment or boss fight. But aside that, the gameplay consist in attacking by choosing cards, there r 3 basic attack cards called 1, 2 and 3 (weak, medium and strong attack) and then 3 special attacks, 4, 5 and 6 (and there are some 7 cards, but they r really rare). The characters attack or perform their turn right after u finish choosing cards, this also depends on the speed the enemies perform theirs, so ur character may act after the enemy's turn, thats also part of the strategy and appeal of the game, u've got to have a quick mind and fingers. xDD
This time u have only one deck for the three characters, which can be a little pain since there r some cards that can be used only by one character, so u have to think the cards will help u best very carefully.
Graphics: still amazing, since you visit the same places as in BKEWATLO except Mira =( , but still looking great, like a painting to me.
Music and sound: now, this is a huuuuuugeee improvement, talking about voice acting, in the first was horrible, but this time is beautiful. The music is as epic as the first game too, ive never liked a OST like these games before.
Overall if u like RPG's u'll hardly be dissapointed by baten kaitos origins, this game is long, interesting and FUN to play, if u dont like rpg's give it a rent.