I already listed multiple things. The game gives you a lot of freedom to do w/e, pick off enemies with stealth, the flying robot, seeing enemies through walls, annnnd regen health. But wait, there's more! From ign:
"The good news is that, while health is regenerative, you can still use health packs on the fly that will heal you quickly and slow down time for a limited period, too, giving you an edge against incoming hordes of aggressive foes."
http://www.ign.com/articles/2013/06/12/e3-2013-killzone-shadow-fall-has-made-me-a-believer
^source
That sounds absolutely ridiculous to me. So not only can I hide and have my health regenerate but I can also heal it quicker and SLOW DOWN TIME? So you can regain health back for free, got a robot buddy to kill shit for you, you can pick off enemies with stealth which never works because it basically means designing spaces where enemies do dumb stuff to allow you to sneak up on them. What's dumb about that is the "punishment" for getting caught is WELL NOW YOU SHOOT THINGS.
The big issue I have with regen health is it SEVERELY limits what the enemies can do. You can't have really have a variety in damage because lol player can just go find cover, so in pretty much all of these games enemies kill you way too slowly on "normal" and ridiculously fast on harder difficulties. No regard for pacing or anything, just straight from the start. That's not really a very engaging or fun way of making a game difficult. It seems like they're just throwing options at the player and not really making that well of a designed game. I've played Killzone 1 and 2, a bit of 3, and none of them gave me any confidence that this game would really impress me.
I'm not calling the game generic or w/e but I'm saying their choice in how health works is terrible. I've seen enough, there's no way they can do enough to make it work. I loathe regen health in shooters because it just bottle necks what you can do with so much stuff.