First thing you will notice is this is one of those games where you hold the DS on its side. If your game requires you to hold the machine itself on its side you become a stand out in the DS community, “it’s one of those games that you hold on it’s side, like Brain Age, but with a ninja guy.” Think different.
For a button masher there is very little use of buttons at all, the core of the game play is done with the stylus. Just scribble scrabble on the touch pad side and your ninja guy is thrown into a cyclone of moves and a very satisfying hit counter. You love the hit counter, and you love those glowing orbs that come out of dead people that grant you special powers. In order to activate your special powers you must go into a drawing mini game.
With lots of save points it is easy to pick the game up and play for ten minutes and put it down again. So of course this means I haven't finished the game yet, this in and of itself is not that uncommon. If you own a DS and you want a game with tight game play and good graphics, I would get Ninja Gaiden: Dragon Sword, well worth the suggested retail price.
A side note, Ninja Gaiden: Dragon Sword has joined an ever growing list of games that have DS in the title.
Advance Wars: Dual Strike
Castlevania: Dawn of Sorrow
Dig Dug: Digging Strike
Fullmetal Alchemist: Dual Sympathy
Guilty Gear: Dust Strikers
Resident Evil: Deadly Silence