tl;dr I'm really not sure how summarise this one.
We're not just desensitized to violence. Hollywood seems to have endeavored to neuter any fight scene of anything that can be construed as really violent in any relateable sense, leaving us only with a strange choreographed dance. No one, really, is getting hurt after all.
But the moment the first blow hits home in Haywire, I found myself wincing. What's this? This is violent! You could hurt each other if you keep doing that!
As much as Haywire looks to put the violence back into fighting, it also looks to take the action movie out of an action movie. Normally, a kind of introduction to the plot is a good idea round about now, but for Haywire it's not really relevant. What plot Haywire does have is relatively token - it's there to link each event, each scene, to another. There's a lot unclear and muddled in there, and in the end everything comes out feeling a bit shaky.
Character motivation, too, seems very much their because it's necessary. With this they do take great care making sure you understand why "X" does "Y" at each part of the story, but you never invest in those motivations or are really convinced. It does just enough and no more, although certain later twists in this respect feel very weak.
Normal action movie fare places a great amount of onus on plot and character motivations, and if you attempt to look at it as an action movie then everything rather falls apart. The script features rather a lot of lines which are just plain clunky, and there are moments of forced whimsy that really don't work. Despite all this, I have to say that I found Haywire to be very much a worthy watch. Scenes are often drawn out, and shot in unusual ways, and the film has a very interesting flow to it. Whilst, alone, this is isn't necessarily enough, the fact that this is happening in an action film that doesn't really work as an action film kind of makes it interesting in a round about way.
The star of the show, a professional fighter leading an all-star cast of Hollywood actors, is very much part of the appeal. She's not exactly a good actress, but she's a damn convincing action heroine, and in that she is effective. This creates a problem however: when she fights the likes of Fassbender and McGregor, you don't ever believe they can stand up to her. In this film, acting itself seems to detract from the strange flow rather than add to it.
This is a difficult film to recommend. For what it's worth, I enjoyed it and you might too. It's one of these films you just don't know until you give it a shot.