It's a bit better than EM.
As for the ending, what exactly are you trying to understand?
In the end, everything kind of goes to the crapper for Chopin - he realizes Polka is dying due to her condition, and the characters in his dream are getting out of control, and is beginning to question if it's a dream at all (ie, Polka & Chopin in the midnight forest).
However, once the party defeats the last uber-boss, Chopin realizes he's still stuck in his dreamworld, and needs to get out of it.
This is why he fights the party, and looses. Near lifeless on the ground, he realizes he's still in this dreamworld, and cannot get out. He gives up on leaving the dreamworld, because of his friendship with Polka (who just jumped off a cliff), and uses the fact he knows it's a dream to re-write the story, and bring Polka back, thus turning his dream into an eternal sonata. Once he gives into the dream, he dies in the real world (as you see in the outside world cutscenes).
Having said this, it's just my interpretation of the ending. My girlfriend was confused about the ending as well. We haven't finished the Mysterious Union, and beat the game the 2nd time around to possibly unlock alot more stuff (since it seems that the 2nd game is a bit different).
Back from the dead, I'm afraid.
