Ok, final update: Gsync does not act nice with this game. The problem came back after a restart of the game and I almost flipped my shit. Then I figured I'd try to flat out disable gsync, and behold, now it's been fine for several restarts.
Performance seems fine at 1440p / Ultra with a 980Ti. The Ultra setting leaves shadow resolution and something else at High though, and settings those to Ultra ends up with me way below 60fps.
VRAM usage goes up/down when changing resolutions, so I'd say that at least it's not an upscale from a static resolution. It does look a bit blurry though, even at 1440p, so I'm going to guess that the theory posted by someone already about it being an upscale from a some fraction of your selected resolution is correct.
There is some input lag that might disturb people used to Gsync/144hz, but nothing too bad. Seems playable.
So, all in all, there are problems, but when it works, it works OK... at least for me.
Finally, someone asked for AA ON vs AA OFF screenshots. So here you are:
http://koti.kapsi.fi/~ramshot/QB_AA_OFF.png
http://koti.kapsi.fi/~ramshot/QB_AA_ON.png
Personally, I can't even see a difference, not in those shots or in-game, so I'm going to leave it off...