Gives me a gritty & dirty FPS experience.
I also find you don't need much more skill nearing the end of the game as you do at the beginning, you just need to find the right strategy to approaching the levels, and get familiar as to where and when the increasing number of enemies come out at you.
What's good
The first thing I noticed about Killzone was the amount of detail in the environments. It didn't feel like a bland and empty space; You do get the feeling you're in a war zone. Especially in the urban environments where there's lots of debris in the area. Things just looked dirty. Things looked abandoned, not never-lived in.
Action. There's lots of it, but It comes at you in bursts so you don't constantly feel overwhelmed by enemy bombardment.
Voice overs. Over all the voice over quality was well done. When I first played this game a couple years ago, it was one of the first FPS games where I thought the enemy BOT comments were realistic to what was going on at the time, which I hadn't experienced in the past. Comments from your team mates however are not always as in context. I will say that despite the quality of the voice work, the character one-liners do get very repetitive.
For the majority of the game, difficulty level can be set just perfect for me, where I feel challenged, but not hopeless. Although some of the later levels did require a few run-throughs before getting it just right.
The objectives for the missions are clear, and I rarely find that I'm lost, or don't know where to go next.
Your team is helpful most of the time. Not awesome, but helpful. They will hold back the enemy if you need to take some cover and recuperate for a minute. They're pretty useless at long range, and will stand still doing nothing, but I'll focus on the good; that being when the combat is in close conditions - they'll pitch in during a fight.
Up to 4 playable characters. At the beginning of each level you can choose which character you will play as to add some variety.
What could have been better:
I didn't find any really big let downs in this game, but a lot of little things.
No jump button. What? The ability to jump in an FPS game has been around for over a decade. In replacement of a Jump they have areas where you can press a context sensitive button to vault over an obstacle, but it's kind of slow to do that in the middle of a fire fight. To the same point, you also have to press X to climb ladders. you can just walk up and start climbing. This is supposed to add to realism I'm guessing, as it causing your character to sling their rifle, but again, it just slows things down.
Aiming is touchy, and harder than it should be, especially in sniper mode. I picked up a sniper rifle once, then left it for the rest of the game.
Bad guys. There's not a whole of variety to them. The guys you fight at the beginning are still plentiful in the end. And although the voice work is good, they all have the same voice.
Weapons reset. Each level is broken up into 3 stages (for the most part). But at the beginning of each level you always start with your default weapons, not the ones you collected from the previous level. Not a big set back, just weird. At least they refill your ammo for you.
Check points. There's an absence of check points in a few of the later stages, which can get tiresome if you die right near the end of a stage, and have to start from the beginning.
Final word:
It's a steady journey throughout the game with lots of action to be had. Despite some of the flaws, I do recommend it for FPS fans.