Brutal but once you get the hand of it, it's pretty good
The graphics are not that spectacular, with the character models being last generation with a little bit of next generation shine, which makes them look a little too plastic. But that's partially due to the fact that Ninja Gaiden Sigma is a port of Ninja Gaiden on the X-Box.
Ninja Gaiden Sigma subtracts some of the missions from Ninja Gaiden but it also adds missions for the lovely Rachel, which is almost a trade-off.
Ninja Gaiden Sigma has almost no real story per say, as it's mostly a hack and slash game so there's no story to speak of. However, it does manage to be somewhat coherent as the story progresses along.
After you complete the game, which takes about a good 15 hours to 20 hours to do for the first go, you unlocks the mission mode, which has a whopping 40 missions, which would take an additional few hours to get through.
My gripes with this game is with the camera that gets in your way at times. The camera is not very good at times and you don't see the enemies at time, so this can lead to your character's death. In addition to the difficulty, this will make you curse like a sailor.
Overall though, Ninja Gaiden Sigma is a good action game and I'd recommend it to any action game fan. This is a good game, but it could have been better if Tecmo fixed the camera issue. Coupled with the lots of hours you can spend on this game, it's more than worth a purchase.