Hmph, game does not run well at all. The framerate you see in the demo is basically how the game runs. I've completed five levels thus far and it is rarely smooth. It always has a bit of a judder going on. Was hoping it would be smoothed out, but no, it's not.
A damn shame, really, as the game is absolutely amazing looking. One of the most impressive things I've seen yet, really. That quality is spoiled by the poor framerate, though.
Game is pretty solid, though, and surprisingly varied. You really see and do a whole lot of different things in a very short period of time. I'm amazed they are able to hit 20 hours with this much variety. I've already seen enough locations to fill an entire game and, yet, they only keep you there for a fairly short amount of time. Usually, when you arrive in those sorts of areas you end up spending a good hour or two with that type of scenery. Not the case here.
If this were simply a rock solid 30 fps it would be the best looking multiplatform game I've seen to date.