Ninja Assassin tries to fix the main mistake of The Matrix—an obtuse, irrelevant story—by basically skpping the story completely. The alleged "plot" of the film has something to do with some kind of government agency from some country stopping some ninja clan from doing something with the Yakuza. Something about gold, perhaps. This summary isn't deliberately reductive to make a point; that really is about as much as is ever explained. It would be silly to expect more, and after the first few minutes of gory action, (more on that later) any attempts to explore the story are pointless, unwelcomed distractions from Rain doing horrific things with a variety of sharp objects.
And horrific things he does. Arms, legs, heads, torsos, swords, knives, darts, fire—they all fly across the screen quickly but constantly and always drenched in an obscene amount of blood. Ninja Assassin is surely among the most graphically violent movies ever created and should not be seen by anyone who even knows a child, let alone the child himself. Whatever-Rain's-name-in-the-movie-is (Raizo) fights in laundromats and on rooftops and in moving traffic, cutting down ninja after ninja (they're still not very good at fighting in groups) in the expectedly cool, Matrix-y ways. McTeigue fully satisfies a need for action by pacing the events more like a video game than a movie, using occasional vignettes of plot only as an excuse to move from one bloody set-piece to the next. God of War II will feel like The Godfather II if taken on after this movie.
Even when judged by its own standards, however, Ninja Assassin has some glaring flaws. McTeigue takes the idea of ninja stealth too seriously at times, often having entire fight sequences happen mostly obscured in shadows. If the point of the movie is to see ninja fights, then it really defeats the purpose when you can't actually see the ninjas fighting. When you are allowed to see the battles, there's way too much reliance on CG effects for blood and certain aspects of the weapon work. The CGI is jarringly bad most of the time, so unlike The Bride's slobberknocker with The Crazy 88 in Kill Bill (which, for the record, is not being counted as a Matrix clone), you never get any sense for the feel of all that blood; it looks more like shiny liquid steel and never actually lands on anything. See this film in a cineplex now because the effects will look downright awful when you see them up close on Blu-Ray in six months.
Ninja Assassin puts on a clinic in making a bad, bad movie that's bad in the best ways. Nevertheless, it's bad in a few of the worst ways too, so considering how little it tries to do, not getting those few things right seems inexcusable. That said, right down to the bluntly honest title, nothing about the advertising campaign would lead a thinking person to expect anything more than what it is, so if you put your money on the counter and come away disappointed, it's kinda your own fault. Besides, you won't be able to take a katana to your attention-starved black-sheep of a cousin or judgemental mother-in-law this weekend, so watching the Korean Justin Timberlake do it instead is just the release you probably need.