Just downloaded it, and have played a little bit.
Well... it's HARD! I know, I know, all the previews said it would be, but really... Believe the previews!

I haven't even gotten to the first save point yet, but that's also because I'm trying out new things, and I'm too stubborn to drink a potion.
First conclusions:
1) The new Intercept move will take some time to master. You need to press block at
just the right point, and I haven't gotten that quite down yet. Then again, I play the game relying on blocks, rolls and counters, so I'll need to rethink my strategies I guess.
2) The new weapon (Lunar) looks absolutely cool, and its combo's make combat seem like a well orchestrated dance. The animations from this game are just light years ahead of the competition I feel.
3) It's HARD

I mean, black ninja's coupled with white ninja's coupled with no upgraded weapons, techniques or health increase??
Oh, and the black ninja's have gotten a new move. A 'grab' that impales you on their sword, and ignores your block. Shit.
As a frame of reference: I've finished it twice on normal, and once on hard, never once having to buy a potion from a store.
Maybe I'll post some more later, when I've actually reached the first save point
