I'd say Killzone finally opening up its gameplay from a pipe-run FPS into one that offers bigger playgrounds where you can choose your own approach is a pretty big upgrade that probably couldn't quite happen with PS3 level hardware (at least with the level of visual fidelity they were going for). And it's still the best looking next-gen game atm.I don't know if Killzone and Infamous will have any new, unique features, I haven't seen any.
And inFamous is a massive leap over the two other games with seemingly much more destruction added into environment. inFamous 1 & 2 didn't really look that great in comparison to games like Uncharted 2 & 3 and God of War III, but Second Son is really a big showcase for PS4 tech.