As good as Killzone looks I have to tell you I am more interested in CoD4 after seeing this video..
http://download.gametrailers.com/gt_vault/t_cod4_e32k7_seaandland_gp_gt_h264.mov
Looks great ! No doubt cream of the current FPS crop (Although the sea looks fake, they added a healthy supply of water splashes to overcome it). I think besides excellent lighting, its strength is the realistic weapons and familiar gameplay, which will appeal to war buffs and FPS fans alike.
I hope Guerilla Games takes this opportunity to push FPS to another level. Afterall they are heavily funded. At this early stage, people are already comparing it to near completion games in terms of visual effects. But as I mentioned in another thread, I hope to see additional dimensions in KZ.
Like even better comrade and enemy animation + AI... Based on the KZ trailer, it seems that facial expressions and character animation will be part of the story telling (instead of just run-of-the-mill audio narration/shouting and smooth walk/run cycle). In this area, it is a little like Drake's Fortune and Halo.
The enemies also reacted in more dramatic ways (as opposed to tactical shooters where the enemies pretty much roll over and dies quickly. Most of the cases you can't see close up of the enemy's face/mask because that's not the focus -- They are just a body with a name tag). In KZ, there'd be mini-bosses and boss characters, which I'd imagine will take quite a beating before they go down.
According to what we know so far, weather effects may play a key role in gameplay rather than just a visual effect. Resistance has tried "shallow" but convincing snow, rain and even glass effect at PS3 launch, now is the time to take it further. Looking at how smoke/fog whirl around the flying platforms in the KZ trailer/demo, I hope this is a hint of further game play elements (Wind !).
As for the lightning canon destruction sequence, I also think they should add more disruption to the final few minutes to make it more difficult/interesting to destroy... but then again, a flying drone came out of no where right after the destruction, so perhaps we will have another hectic battle ahead of us. The level is still in pre-alpha, so I'd imagine they will play balance it to death.
For now, I think KZ 2 has started work in more breadth and depth than most FPSes (e.g., destructible environment). However I hope they don't forget about the basics... like what Resistance has already achieved months ago (Silk smooth animation, fast + lag free online, and fun gameplay).
Lastly, I hope Sony stays true to their Game 3.0 vision. As technologically exciting as KZ 2 is, I believe something like LittleBigPlanet will offer more impact and reach in the long haul.
(Now that I said it, can I join the KZ alpha and beta testing now
).