Don't play FPS so I can't comment on the killzone comparison.
Imo, a good comparison is the shadow of mordor game...Battle felt asventure like in that game and stealth was key. Loved that game. 8.5 and above.
I'm surpised too see a couple of reviwers show disdain and dislike when few find it a perfect game and most people have it between 9 and 9.5...I can't imagine this game not being fun and immersive with those across the board positive reviews...
Video game jounrnalism can be really weird. I suppose its like the NBA when voting for insividual awards.