That is not Sienna Miller's face. That's a hybrid of Maggie Gyllenhaal, Joan Rivers, and a 7th grader's carefully-shaded pencil drawing of a woman with an afterthought of sunglasses. It's not Sienna Miller and it might not be human.
At least Channing Tatum captured the proper listless melancholy of being in an elite military team. Driving awesome vehicles with ridiculously powerful weapons may be cool, but there's also a sadness that comes with it. There's a reason the Duke action figure comes with a rocket launcher and a poetry notebook.
G.I. Joe International Poster [Empire]