I never played any of the other Ninja Gaidens, but that doesn't matter at all. This is one of the greatest games off all time. The reason I gave it a 9 is because the camera is pretty bad. Most of the time enemy is right in front of you and you wont know it. On the good side the combat never gets boring, you get to play as the coolest ninja EVER, and it's so difficult. Thats right it is good to be hard in this game. Finally a game that you wont get bored of in a day. Even when you beat it(I'm no were near the end) you'll still play it over, it's that good. So no matter what you like(whether is true ninjas, bunnies, or Naruto) at least rent the game.
This game is a must have if your a hack and slash gamer like myself. Other games that use button mashing to complete an objective get boring after a while, ninja gaiden is the same way, however there is more skill involved when playing ninja gaiden because the enemy AI are not brain dead like other games. Ninja Gaiden is not an easy game to pass and that is what makes this game stand out from the rest. If you like to spend endless hours replaying a level to beat the "boss battle" then I recommend this game, if you want something that is easy and doesn't require any skill, then move on this game is not easy.