I didn't like it. I felt it was gimmicky, and that they used the gimmick to stretch ten minutes of story into eighty minutes of film. The characters, such as they were, ranged from "annoying" to "really annoying), and it's astonishing to me that half an hour goes by before anything happens. That's over a third of the movie!
And why is it that in movies like this, where it's all handheld footage shot by a character, it's never a character who can hold the camera steady? This movie's tiltier than a broken pinball machine! And when you see a giant crazy monster, maybe you should just hold still for a second. I mean, if you're so obsessed with the camera that you're shooting even while running for your life, you'd think you could get better footage. But no; as soon as the monster heaves into view, it's all "Zoom out! Pan left! Zoom in! Tilt it more! Whatever you do, don't look directly at the monster!" The characters get pretty good looks at it, it's just the audience that doesn't get to play. That not only bugs me, it takes me completely out of the movie. Handheld shaky cam is not, for me, remotely immersive. It's whatever the opposite of that is. It makes me sit in the theater and think "Oh, look. They're doing something obnoxous with the camera." I should not be wondering what the cameraman's name is in the middle of a movie.