Ok, I went to see Ninja Assassin the night it was released! I have been excited for this movie for say 5 months because I am a fan of the main actor Bi Rain. OK first off, this is a movie for people who actually appreciate martial arts and gore. If you find that boring, you won't like it. It's a movie that either you absolutely love or you absolutely hate. I LOVED it. The blood was obviously fake, but it was excessive.
I enjoyeed the vast amounts of killing and violence. And everything in the movie is real (aside from the killing). The martial arts are all real, no stunt doubles were used for the falls, and Rain is all real! He built up his bod just for the movie so I don't want to hear anything like he looks airbrushed!
The plot was ok. Instense even. I think if the movie had been as long as say....A Lord of the Rings movie it would have been better because they just tried to finish the movie in the short amount of time they were given and well, it was pretty good the way they tried to rush it. Not too rushed, but not much resolved.
Go check it out! It's not scary, but has hard core action scenes. Enjoy the blood and Rain ;)