The code OPS reviewed can not be the review version. A week ago i've spoken to Alastair Burns (producer) and he told me the game is not done, period. In fact, he was in such a hurry he told me 'I cannot talk to you any longer, must get back to the office and work'.
And it is still uncertain if the full version will have 16-player online support. Don't know why, must be problems with fps, lag and more of this. 12-player online is more likely.
edit: Killzone (from what i've played) is a 'good'. a "EDGE/GamesTM - 7/10, OPM - 9/10"-o-score. I think people will enjoy it as it is far better then the usual PS2 FPS crap *cough*MOH*cough*.