The best Kingdom Hearts yet! One of my favorite games of all time.
Story: Birth by Sleep takes place at the very beginning of the Kingdom Hearts time line, featuring three new main protagonists, Ventus(Ven for short), Aqua, and Terra. All of which have their own gameplay, story, different combos, ect. The three have been best friends for years, and after Aqua and Terra's mark of mastery exam, the three depart, I'm trying hard not to spoil a thing by the way, and they go out and visit new worlds.
Gameplay: The gameplay is slightly different from past Kingdom Hearts games, but not too different. You have two types of command decks(No, not a deck of cards). The first command deck, the one you use during combat, has up to eight command slots which can hold special attacks, magic spells, items, or other things. The second command deck is mandatory, it holds your natural controls(Jumping, air dashing, ect.). You also have these amazingly helpful attacks called "shoot locks". Press L and R at the same time, hold them down, target some enemies, and unleash a variety of target based attacks.
Music: It's square enix guys, of course the music is gonna be amazing. Although this game, in my opinion, has the best soundtrack in the series.
Graphics: The graphics look the same as KH2, but are probably a bit better.
Replay Value: Oh man, there's tons, and TONS of stuff to do after you beat the game. There's a mini game featuring a board game, there's an arena for getting useful items which you can do by your self, or with friends, which include racing similar to that of Mario Kart, only, you know, not as good. Disney Town especially has the most replay value out of all the worlds. There's the journal you can 100% which'll leave you entertained for weeks. And lastly, there are two secret bosses for each of the three characters.
Final comments: In my opinion, Birth by Sleep is the best in the Series. I highly recommend this if you're a Kingdom Hearts fan. Hey, even if you're not a fan, pick this up, you might just end up becoming one.