I picked this up with my PS4 yesterday, and it's really, really good.
The combat feels like a mix between Assassin's Creed and the Arkham series, the Nemesis system is great (I've had a couple of run-ins with one particular Uruk, and after beating him once by setting him on fire, he was badly scarred on our next meeting and had developed a weakness to fire) and it looks fantastic. The frame rate appears locked at 30fps, but there are no discernible dips no matter how many foes you take on at once, and the weather effects and textures are superb.
It feels like a proper next-gen game, the kind of thing that 360 or PS3 simply couldn't run, at least not without some major concessions.