"47 Ronin" got really bad reviews. As I write (early 2015) it's sitting at 14% on Rotten Tomatoes. And they're not wrong: it's ponderous and pedantic. Consider what the bad guy says to the ronin early on: "You're ronin now - masterless samurai" ... and he's saying that because it's for an American audience who may not be aware that that's what ronin has always meant. The actors are almost uniformly Japanese, but they're being made to speak English. And some of them just aren't very good at it. And they've taken this very famous, even revered, Japanese story about the 47 Ronin (Wikipedia) (there was a historical event this was based on) and grafted on a "half breed" (Reeves' character Kai) and witchcraft. Neither of which fit terribly well. And then there's the acting. If you can call it that. I really liked Hiroyuki Sanada (who plays the leader of the Ronin) in "The Last Samurai" as the grim master swordsman, but apparently that's all he's capable of. Of course when the other lead actor is Reeves, no one is getting upstaged - in fact, it's safe to say no one did any "acting" on this set.
And yet, and yet ... Perhaps it comes from watching years (decades?) of martial arts movies. With some bad movies I'm able to see through what they were doing to what they were actually trying to do, and enjoy that. My tolerance for bad movies has been going down, but decided to make a resurgence just in time for this movie, and I quite enjoyed it. Go figure.