Thumb hurting.
Graphically, Nightshade is ok, with nice models and good animations. The most appraisable feature is the frame rate: rosk-steady and smooth during all the game.
However, the gameplay only makes this game annoying. First because Nightshade herself is the first ninja I know who don't have a recovery jump. As you try to go through the swarm of enemies, you wil have to deal with an evil quota of movements during each jump: you are allowed to use one dash, one double-jump and one kick each time you jump from solid ground or you hit an enemy. Sounds good? But it doesn't works nicely. More than often you will be in the middle of a maneuver in order to complete a "tate" (a nice feature done by killingall the enemies onscreen in a row) and a shot coming from nowhere will knock you off your feet and, in the latter stages, inside a pit. After a couple of minutes it will get annoying and you will eventualy grow tired of holding the lock-on button. But that's just the beginning: there's a sequence of actions you shall perform in order to open the enemy's defense and start hitting it. Think fast: jump, double jump, dash, kick, slash, dash, slash, slash and double-jump, dash, kick... ad infinitum. Whenever you try to hit an enemy without opening its defense before, it's the end: your sequence will break and you will inevitably be thrown into a pit or lose all the enemies you killed before...
The game is tough, yes, but it goes boeyond frustration with such bad controllers and lame storyline. The camera action is also annoying, but I'll save my words and avoid comenting all the bad thing here.
Just stay away from Nightshade: buy Devil May Cry, instead! It's as hard as Nightshade, but much more fun!