Much of the movie looks like it was filmed with an I-phone for Youtube.
Yes, there are a lot of very cinematic epic shots like the opening battle and the horseback chase of Hugh Glass by the Arikara, but a whole lot of this looks like one of the Mountain Men was filming everything on his i-phone to post on social media.
The constant movements of the camera from face-to-face, the zooms, the odd, distorted focus in some shots... It's very much what an amateur person's clips look like on Youtube or Twitter.
This must have been a conscious decision by Inarritu to lend a sense of the contemporary to the story, to show it to the audience the way they would see it if it was happening today.
I'm not sure if it worked, though, because I found these scenes distracting.