Bottom line: The PS4 and the FPS-genre in general need great-looking, fast-paced, futuristic sci-fi games that push imagination, gameplay, and graphics. Killzone is known for these in spades, but misses opportunities that could have pushed it to further greatness.
Pros:
-Stunning graphics, they are just plain gorgeous
-Killzone-esque weighty gameplay
-Online gameplay customizable, frenetic, and yet approachable
-Itches a futuristic sci-fi scratch
Cons:
-Plot is not memorable, even though situations are
-Missed opportunity for reboot of memorable franchise
-Campaign Couch Co-op sorely needed
The best memories I have of Killzone are from Killzone 1, which did not have the best graphics, but utilized beautiful and distinct environments to achieve a level of recognition I still can't shake from the top of my list of memorable FPS experiences. The weapons were always weighty and unique, and the AI was always more believable and natural than other games save for Halo. I wish there was Co-op because it would have given me a genuine reason to own 2 controllers and invite people over to share in my next gen purchase.