Killzone 2 was crap, at least i thougt, thought it was gonna be good, went out and bought it after reading some awesome reviews, went home and played, gave it good go as well, and felt like i wanted to throw it out the window.
It was really linear, just go over there and shoot, go there and shoot and when i say this i mean you can only walk one way and then shoot, if something is straight ahead of you and you think it would be better to go to left for a better shot, you cant you can just go straight, best way i can describe it is it is like time crisis but instead of just being moved forward automatically to your pre-deterimed shooting spot you have to slightly move the joystick.
Maybe killzone 3 is better but 2 really got to me as by the time i got home for the night after work, and having no work for the next day, all the games shops are closed and none are nearby anyway, iwas stuck with it.
I played the multi player demo and it was AMAZING. Really enjoyed it, and pretty much made it my FPS of choice when the demo came out. Haven't gotten around to buying the actual game though as midterms came around, and papers due.
Buying it very soon though. Really enjoy the online, and hear the single player is great too.