Ah, Hibana... There is so much -good- about this game it makes you want to forget all the bad aspects of it.
Well good luck. After three months i finally beat this, but it is --hard--. Very hard. Sega claimed that they revamped the difficulty so that humans could one day hope to beat it, and that's just barely what they did. Now the gameplay is wonderful, the same glorious stealthdash we all fell in love with in shinobi. And there are baddies everywhere, however...just like before, things like: A Floor, are not often below you. The levels have nothing in the way of effective checkpoints, so you better do every level perfectly, or you get to do it all over again. Whee!
Couple this with the fact that many bosses are virtually impossible and you'll be tearing your hair out inside a week with this game.
Now the bad news aside, the game plays very well, the new addition of "adjustable" difficulty gives you some margin for error. The graphics are adequate but could have been better (jaggies galore). It's worth a rental first. The moment you yank out a tuft of hair, take it back, otherwise, enjoy!