Okay... I played it for an hour yesterday. So far, I dunno... it hasn't grown on me yet. There's a lot of Japanese dialogue in the game, which is hard to read at times because the kanji is a little small (not to mention my Japanese reading abilities aren't that great yet). I wish I understood the underlying story, but so far it seems basic.
Gameplay, it's okay but it's not really capturing my interest. The game's character sprites are about the size of the people in any Castlevania game, but they don't animate as well. Attacks I've seen so far are throwing ninja stars and using your sword, along with jumping. It's very similar to Kage 1, but you have a life bar... and you seem to be able to take a lot of hits. I didn't die at all during my first hour of gameplay. Also, it uses the two screens fairly well. You don't experience as many cheap hits as with Contra 4, but then again you don't die in 1 hit either.
There seems to be a branching map after you clear a stage. You also have an option to play one of 2 characters in the beginning (1 male, 1 female). I played the dude and he's okay so far. It's classic Kage I would assume, although you do earn new abilities as you progress in the game, from what I can tell. You can slide and you can split yourself into three (2 mirror images and yourself, like in Ninja Gaiden 2? 3? I forgot).
This game is okay... it hasn't grabbed me like Space Invaders or Arkanoid did... but I will have to play it a little bit more before I can lay down a verdict. Unfortunately, I have been caught in the clutches of playing Ace Attorney 4 and Space Invaders Extreme, so this game is a little bit lower on the priority list for now.