PS4 version
I've played the first two missions of the game. The first one was very small and kinda a tutorial. Things open up in the second mission though and I guess things will be like that with future missions.
- Graphics are much better than v.2. The IQ is surprisingly good and obviously 1080p helps a great deal. Framerate is mostly smooth but drops a bit with explosions etc. But nothing that distracts. Zero screen tearing thus far.
- So for the gameplay itself: The game is definitely more open than v.2 (at least from what I remember). You get primary missions, then you get secondary missions along the way. Checkpoints are pretty well placed, and there's been quite a few times where I had to restart because of failed secondary missions. When it comes to x-ray, I feel that it hasn't changed THAT much. There's a bit more details but mostly the same as v.2. Still cool though. I liked the level design in mission 2, quite a lot of freedom. I'm playing on the Sniper Elite difficult level, which thus far has been pretty easy, so I recommend not to go lower.
I haven't played either of those games, but the way you describe them, definitely Dishonored-like.