I know there's some, but I have no idea how much. Also, you can play through the game as a girl now, and it changes some of the character relationship stuff for that (like Elizabeth gets replaced by a male counterpart), but again, no idea how much that changes things (though I like the girl's character design). The only other thing I know about is there's supposed to be a super-ultra-hard mode that puts the hard mode from the original game to shame.
I mostly want it because I always wished the game was portable when I played it, and I really didn't get very far despite how much I was enjoying it. If I actually had this portable and was getting language practice while playing, I'm pretty sure nothing would keep me from finishing it barring breaking my PSP.