Honestly, I'm getting the PS4 for Infamous, followed by Destiny. Followed closely by future titles that I can't even imagine right now.
Also, I looked at Metacritic. Killzone has 10 positive reviews all scoring it at 80, 85, or 90. With 8 mixed reviews most scoring it as a 70. The one that scored it as a 50 (looks to be a 5 out of 10) seems more upset over story elements, "lack of innovation", and seemed to be more pissed at having to play the game than anything in the game. There's literally a tweet of the author of said review effectively begging to not have to review Killzone. Me thinks he may not be unbiased.
I'm not going to defend it, as I haven't played it (despite having a copy sitting on my desk right next to me), but I really doubt Killzone is any worse than CoD. I'll be mostly playing it for multiplayer and to tide me over till Infamous hits the shelves. So worse case scenario, it's not the best game I ever played, but it's liveable.