I got this from the First to Read program.
The Knife painted me into a world of a black ops unit in Afghanistan. It made the rhythm of that life real, with the sudden signals to move, the lack of information, the mind-numbing waits and the lack of sleep. I have no knowledge to decide whether it's true to life or not, but it's powerful and enveloping.
It's also dark. You can feel the imperfection of it all the way through, like a horrible calamity is always just on the next page. Something will go horribly wrong. Mistakes will be made. Mistakes were already made. Perhaps these men aren't who they want to be. Maybe these decisions they face are inhuman. Maybe the only way to live this way is not to think about it. But the main character, Shaw, does think about it -- there are long wait periods and it seems unavoidable.
It's a really effective and powerful read. It's also gritty, dark, uncomfortable, and vulgar.