Haywire tells a familiar story -- after a mission goes wrong, a mercenary seeks vengeance on those who betrayed her -- but tells it with great style and just enough surprises to keep it interesting.
Gina Carano has the lead role; she's not much of an actress, but her background in mixed martial arts does make the fight scenes more credible than usual. And Lem Dobbs' screenplay doesn't call on her for too much emoting; her character is a stoic, taciturn, mysterious kick-ass fighter without much personality beyond that. Soderbergh has surrounded her with a strong cast of men (there's no other significant female character) who carry Carano through the dramatic moments: Ewan McGregor, Channing Tatum, Michael Douglas, Antonio Banderas, Michael Fassbender, Bill Paxton.
The movie is beautifully photographed, and the action sequences are staged cleanly, without too much frantic editing or camera movement; it's always clear where the characters are, both in relation to one another and in relation to the room they're in. A hotel room brawl between Carano and Fassbender is especially well done.
The story is, as is conventional for the genre, more convoluted than it needs to be, and withholds too much information until the final big "and now we explain everything" info dump. But it's no more confusing than the Bourne movies, for instance, and the explanation is presented convincingly enough that you won't spend too much time worrying about loose ends.
It's a pleasant B-movie, which is all it seems to be aspiring to.