You've read the reviews. This game has upset quite a few people. While Gamespot gave it a 5.5 saying it's “all flash and no substance”, IGN gave it a 3.0 calling it a “bloody disaster”. Sure, it's bloody and has a whole lot of flash, but is it really as shallow and disastrous as they say- Shallow- Yes. Disastrous- Not really.
For someone who hasn't played a Ninja Gaiden game before, this instalment is a nice introduction to the series as it won't backhand you in the face when (not if) you fail. The game rarely requires you to use any advanced skills and it will do a lot of the work for you (e.g. Your bow automatically aims).
However, for veteran players, Ninja Gaiden 3 is a game that you'll want to stay away from. The game holds your hand from finish to end, and pushing any button besides SQUARE is rarely necessary.
As for the graphics and story, well, they're pretty average. When NG was released on the original Xbox, I was in awe of how beautiful the game looked! I can't say the same for this one. It's not the worst looking game, but the graphics look a bit dated.
Also, the story isn't anything to write home about. I can see where Team Ninja tried to take it (i.e. Make Ryu seem more human), but they didn't take it far enough. There wasn't enough character or story development despite there being quite a few cutscenes. Quite often I found myself wondering why Ryu is even bothering killing all these people. However, it really makes me wonder why Team Ninja decided to be so story-centric with this one as I don't know many gamers who play action games for their stories. Word of advice: either go ALL the way with the story or don't even bother.
Overall, Ninja Gaiden 3 isn't a bad game. It's actually a pretty decent hack 'n slasher and I'm sure newcomers will get some fun out of it. For NG veterans, however, it is best you stay far, FAR away from this instalment.