I thought Killzone one was supposed to be kinda... Bad.
Definitely not a bad game. Criticisms were highlighted due to the unfortunate misstep of a games publication calling it "The Halo Killer." From that point on everything about it was compared directly to Halo on the console which was obviously superior for FPS games.
Killzone definitely had problems which came from the technical limitations of the PS2. It was not designed for a game like that, but Guerrilla still managed to pull off something really unique and interesting for the platform. There's nothing else like it on PS2, and FPS games (the Killzone franchise included) suffer from homogenization this generation, so there's also nothing quite like it on current consoles either.
As I mentioned before, the squad system is very cool. Each of the playable characters can be selected at the start of the mission and each one has their own unique playstyles and starting weapons. It also has some rather open environments which are fun to explore, as opposed to the endless corridor that is Killzone 2 and 3. And the story is much better, utilizing the Helghast as much more than the cartoon villains they became in the sequels. Hakha's an awesome character and his story is probably the best part of the franchise.
Definitely not a perfect game, but it got a really bad rap that it didn't quite deserbe on PS2. If you were willing to put up with a little bit of jank, it was a great experience at the time. Dated by today's standards, but the fact that they're willing to go in and fix a few things like the controls means that hopefully it will be a solid remaster.
