From the GameSpot hands-on with it:
- Almost no HUD during play. No health bars, similar to Gears of War.
- Full physical environment (shotting a canister will send it flying down a hallway)
- 7.1 surround sound
- Cover-system similar to Gears/Rainbow6/etc. Using L2 to lock onto an object then lean out behind it.
- Not all cover is created equal. Some cover, like cement blocks, can be blown away while you hide behind it.
- Insane detail/graphics/level-of-post-processing used to create a really gritty environment
- Improved hit-response system. Shooting someone in the face will kill them different than the arm, chest, leg, penis, etc.
Update #1: Some hot new screenshots just in:

The first Killzone competed with Halo, and now Killzone 2 is going to compete with Gears of War.
I think you meant “kick it right in the trash” =)
Hmmmmm… we’ll see.