After the first Killzone I tried to avoid the hype of this right up till it's release. The first was abysmal, I really looked forward to it, so much so that it was a day 1 purchase for me and what a waste of money. Thankfully this is nothing like the first!.
This game is so good that I still play it, well occasionally. The single-player isn't bad, it's too short as usual and the story isn't something you'll remember forever. There really isn't much of one and I feel that the Gears of War games on 360 have a better story. But the story doesn't matter too much anyway as this game is all about the action and there's plenty of it!. It's got some pretty awesome boss battles particularly the last one. But to be honest I think Gears has better boss battles too. Another think this game has in common with Gears is that it has fantastic graphics but it is far too grey and black as there's very little colour here.
So what does this game do better than Gears? well it has some very addictive multi-player with all the usual modes (Team Deathmatch etc.) and they have released 2 new map packs and there's a third on the way meaning that's there's plenty of maps but they do all tend to get boring after a while and a few weeks after buying this you'll probably put it down and forget about it only to return a few weeks later!.
So in short this game is good fun online and off but it wont last very long and I feel that Gears of War has a much better single-player.