I spent last night playing a bit of Knack, Killzone, & ACIV and I'm really enjoying all 3 so far!
I can see why some people wouldn't enjoy Knack considering how simplistic the gameplay is, but I'm a huge fan of platformers so it's A-okay in my book.
Killzone is really impressive visually, but I've only played 2-3 chapters so far so I can't say it's significantly better or worse than other FPS games I've played.
ACIV is
fantastic so far, it seems like they ironed out all of the gameplay problems from ACIII and the graphics are gorgeous on PS4!
My only gripe is that I haven't been able to get on PSN at all yet (I
just tried again about 5 minutes ago), which is really frustrating considering I see people on my friends list playing Resogun.