Clearly there were no ninjas at work on this one. It's a total rehash of the equally bad `70's flick. The acting is good (particularly Julia Stiles, who should've known better) overall, but the only time this movie comes even close to scary is a couple of cheap shot "boo!" moments. Just... bad.
According to the movie, the son of Lucifer can only be killed by these 7 daggers, which must be thrust into him to the hilt in cross formations, and this must be done on sacred ground. In other words, this movie needed a ninja, and didn't get one. The presence of a ninja makes any ground sacred, and a drunk ninja with epilepsy could accomplish the required stabbiness in his sleep.
Moral of the story: without ninjas, mankind is doomed.