I saw it this afternoon and found it a right passable way to accompany a glass of sangria. Jcomp, you're right, Tim Olyphant is underrated and some of the best things in this film were the natural reactions to standard horror film tropes. There were lots of "shit, shit, shit"s and "Ow!"s that made the characters believable.
It was not without its flaws, one of which was a shocking bit of bad dialogue. Our heroes are in a car, the only thing moving on a wide open road, when a gunship helicopter dives past overhead -
"Did he see us?"
"I don't know."
Lol!
And there's a scene I suspect was edited to death because the camera makes a big deal of a woman contemplating a drinking glass and a bottle of water, but nothing happens.
They do a good job of corralling the right amount of gore and the Stryker saw scene is nothing short of brilliant.
All in all, a decent horror flick.