Mercenaries as I understand it. There has been a bunch of outcry about it, as the chinese director of the chinese funded movie casting Matt Damon is Hollywood whitewashing or something.
I don't care about any racial implications, or anything like that, I just can't get over how goofy it looks. It's like here's a bunch of warriors fighting monsters along The Great Wall of China, cool! And now here's Matt Damon... wait, what?
A paycheck is a paycheck, I guess. Now part of me want Matt Damon to star in a string of seemingly random crappy films ala Nic Cage (no hate, I love Nic Cage).
Edit: An an aside, I don't think you can call it whitewashing if he's playing a European mercenary. A European mercenary would be white. Now, if Matt Damon had been cast as Cao Cao in The Fall of the Han Dynasty, THAT would be whitewashing.