Some screenshots from photo mode (field of view and/or depth of field modified in some of them).
Huge and hugely varied landscapes. It feels to me like definitely one of the largest on-foot open world games ever (there are mounts but I don't find them that useful most of the time, maybe if you decide to play without using fast travel).
I know this is a photomode thread but my God look at the amazing visuals from some of the scenes of the world from this tech video about Horizon's Decima engine. The video has no spoilers at all.