The very idea of Batman and company being transported back to feudal Japan is an idea that had a lot of potential. As it was, the preview of the film gave me the impression the movie, while sci-fi in that it's a comic book movie and there's time travel involved, made me feel like I was in for a samurai epic (despite the fact that the title is Batman NINJA, yeah, I'll get to that later). What I got instead was a completely nonsensical story that just happened to have Batman in it. Fair warning, spoilers are following.
So first, Batman himself. I can certainly appreciate that when he loses all of his tech and gadgets that it would be something of a setback, after all, Batman is kind of defined by his cool toys. However, it was really annoying when he kind of fell to pieces about it. That and a disturbing lack of intellect that the guy is known for did not feel like Batman, who is not only one of the smartest investigators and tacticians in the world, but does not limit himself only to his gadgets. Batman spent years training in nearly every martial art on the planet, which means he is an expert in hand to hand and weapons combat. He might need to adjust his tactics if he lost his tech, which I have no doubt he prepared for, but he wouldn't suddenly go through what amounts to an identity crisis because of it. It just didn't fit with the character.
The other really big issue I had with the movie is that they took what could have been an outstanding feudal Japan storyline and turned it into freaking GundamPower RangersVoltron insanity. Forget the fact that there's all of this massive, sci-fi tech with absolutely zero origins as far as where the actual, physical materials to create computer monitors and holograms came from. This isn't even something as neat or quasi-believable as Steampunk, which MIGHT have made sense. No, we're talking about giant freaking ROBOTS. I realize this is movie is in anime style, but this went beyond ridiculous. When the robots of the five major villians came together (a la Voltron or Power Rangers), that was almost as bad as when a ton of monkeys first formed a giant 'man' that could actually fight, just before combining with an equally huge amount of bats to form an actual, no BS, giant biological Batman fighting 'robot'. It was absolutely insane, and if this wasn't a Batman movie I think I probably would have enjoyed it. The problem is, this WAS a Batman movie, and so doing all of this crazy Japanese anime mech nonsense took me completely out of the movie.
Then there was the characterizations. They weren't horrible, although the choices made for the looks of Poison Ivy and Catwoman were a little odd (Ivy with pink hair and Catwoman with very light brown hair?). Again, what bothered me most was what they did with Batman. The guy is a master at pretty much every fighting style known to man, which includes weapons. Hell, he studied ninjitsu and mastered it, which would include using a sword. Even if we were to believe that somehow the Joker, a man who, while reasonably capable in a fight, is NO WHERE on par with Batman's ability, somehow was able to learn fighting skills during the years he spent in Japan before Bats showed up, they still wouldn't be near enough to Batman's to put up the level of resistance he was capable of. Joker was always such a threat because he was insane, and thus hard to predict sometimes. He was never an expert martial artist or fencer.
And then there's the whole 'ninja' thing. Other than a ninja clan that basically worships Batman via prophecy (because of COURSE there's a prophecy ding), there's no 'ninja' involved with Batman, despite the fact that the guy actually is the ultimate one otherwise. The armor he ends up putting on is all samurai, right down to the katana, with not a single trace of ninja in sight. I guess that might be something of a nitpick, especially since it showed that was going to happen in the trailer, but I was asking the same question back then: "Why is Batman Ninja wearing samurai armor?"
There's plenty more, but, honestly, between this, 'Batman and Harley Quinn', and the live action 'Justice League', it really feels like DC is deliberately trying to get people to not like or anticipate anything with Batman in it anymore. I don't know if that's the case, but these days, if I see a DC product with Batman I'm pretty much expecting it to suck.
Review by Paradox-Warrior from the Internet Movie Database.