Killzone multi (at least me me I haven't played them all) is more twitch based then tactical. Run and gun seems to be the mindset most people play with. Pretty n00b friendly but you will die allot before you figure out what is going on.
Yeah, better reflexes will be needed, but the class based abilities will make gameplay a bit more diverse. You can't just run and gun when there's air support drones in the area or a turret around the corner. I always felt KZ2 was way more tactical than the Modern Warfares because of the class system and the weightier guns.
Good class to pick up for beginners might be Assault. Their primary ability is the Nano Shield, which can block enemy fire. Even though it can be taken down, you can survive just a long enough to kill someone or run to safety. Support class is also a good bet, since you can get Revive Drones or Turrets that can help you rack up kills.
My advice for new players would be to stick with your teammates, and support them with class based stuff like supply boxes or revives (support class) or throw up a nano shield (assault). This will give you time to figure out the game, learn the maps and not die so much (as opposed to just running ahead of everyone and facing 2-3 enemies by yourself). You'll rack up points for doing this, and these actions will also count towards completing challenges (ex- revive 25 teammates). You unlock attachments for guns by completing challenges. And play around with the control sensitivities. Maybe start lower, to get used to aiming, then slowly bring it back up when your reflexes improve.