[quote name='@FIF']What's the upside for Killzone 2 and 3? I hear that they've got a great cover mechanic and good multiplayer, but they seem like pretty derivative FPS's. Is 3's single player any good? Digestible without playing 1 & 2?[/QUOTE]
KZ2 and KZ3 are very different in multiplayer versus. KZ2 has much bigger maps and is a bit slower. KZ3 is like CoD on drugs with smaller maps and faster gameplay (it also had insta-kill melee, while KZ2 does not, though it does play a short animation, so it still isn't as quick as it is in the CoD series). I enjoy both of the multiplayers and they're so different that KZ3 isn't necessarily an "upgrade"--just different. Both games are unique because their class system allows significantly different gameplay between medics, engineers, etc. I would play way more of both of them if they were on Xbox where most of my friends are and I just like the interface better. If PS3 were my main system, both of these titles are a must. Hell, PS3 isn't my main system and I still consider these a must.
I've only played a bit of the campaign of KZ2 and none of KZ3 and it was pretty fun, nothing too special (again, don't play PS3 games much).