So I just beat Killzone 3 on Trooper, and it felt like Elite on Killzone 2. I think somehow the game glitched and upped the difficulty for some reason.
 
I could turn a corner and a single Helghast with a Sta52 could kill me in like 4 shots. I got meleed a few times and they killed me in one hit. During some of the "on rails" sections, if I got hit by just 2 or 3 missiles I was dead.
 
To get a good idea of how fast they could kill me, if I had full health and started to pick up ammo from a crate, or do a brutal melee, an enemy could kill me before I was done with said action.
 
Did anyone else have this experience? I really don't know what happened, but it was really annoying. It wouldn't have been so bad if I ended up getting the Elite difficulty trophy.

The enemy AI is more accurate than the previous game.  They are also smarter as well. Word of advice: don't use brutal melee, use cover, and stay close to Rico.  This is a harder game than Killzone 2.

Thanks for the KZ3 PR, but I know how to play the game. I use cover, but they still pick off shots anyway. I don't see how if what I played was truly the Normal mode, then how it would be possible to even play it on Hard, or Elite. I had absolutely no problem going through the demo, yet when I played the demo area in the full game I got destroyed. I honestly think my game glitched.

finished the game on hard, it was a grueling experience I can't believe there's a harder difficulty! The on-rails sections must be crazy for elite!

i beat it on trooper and I would die in about 3-4 shots as well, but it wasn't that bad.