This is a movie about Ninjas doing Ninja things, being stealthy, practicing bad-ass moves, and killing lots of other Ninjas.
If you don't mind a plot that comes straight out of a not very good video game there is enjoyment to be had here. Sho Kosugi is excellent as the master ninja, and a great choice for throwback fans of much better Ninja films like Revenge of the Ninja (last time I saw it I was 8 years old so...) . Rain (the hero ninja) barely says a word through the movie and when he does he sounds a lot like another immortal swordsman, Christopher Lambert.
Unfortunately the Wachowski siblings seem to be getting much worse at special effects. Some of the scenes look absolutely unbelievable and the Ninja training ground almost looks like a student work for a 3D class. It must be noted that the extremely graphic decapitations look great though. Each decapitation is enhanced with buckets of blood that will make any Tarantino fan giddy with dark and kind of disturbing joy.
If you're looking for a realistic Ninja movie (I know I am) I guess you'll have to Watch Leon again and pretend he's Asian. There are a billion plot holes here, Ninjas are un-killable until the movie decides they should be cannon fodder. Your suspension of disbelief will be pushed into overdrive but in the end, a movie about Ninjas doing Ninja things is always going to be at least decent. Well if you're into low art anyway.
Oh and the movie gets an extra point for playing Being Boiled by Human League during the end credits.
