The framerate's not going to be perfect; even on PS4 there are areas that drop below 30fps. Still, Digital Foundry seemed fairly positive about their experiences with it, so I don't think it'll be too bad.
True. My issue isn't slowdown but stutter though. Where the framerate is more or less 30 but will suddenly jerk down to the mid twenties for an instant and then snap back to around 30. I think a lot of that will be ironed out in the end, we've seen that multiple times now. But it's definitely distracting in this footage.