It is really hard to appreciate the KZ lore after reading all the Halo novels, comics, short stories, and watching the blurays, and video games :P
I'm open to playing future Killzone game, 2 & 3 had some potential, but the story and lore certainly don't match Halo and Gears. I guess xbox fans are spoilt for choise when it comes to shooters. But, there is something about the sci-fi trench warfare stuff about Killzone that I do like.
Killzone SF looks very different to Killzone, it could pass as a new IP if it had a different name. The problem lies with guerilla games. Once they hire better talent and creative guys, they have a shot at delivering a game on par with other shooters.