This game is gorgeous. As a launch title, it does a great job of showing off the power of the PS4.
Having said that, graphics aren't everything. The campaign/story/what have you starts off strong, even for one who has never played a Killzone game before. But, about halfway through, it starts to slip, and it ends with less of a bang and more of a whimper. It certainly sets up for a sequel, but does it really need one? That is the question.
Multiplayer is definitely a change of pace from other games I'm used to, and the OWL adds a tactical twist. However, it's not nearly as useful as in campaign, and it acts more like the armour abilities of Halo, where you can only have one at a time. They can be useful though if you both plan ahead and are a quick thinker. Otherwise you'll find your shots blocked by shields on all sides while the enemy is free to shoot at you. Teamwork is essential in this game, but as usual, keeping voice chat on is bound to be more of a frustrating experience than playing the game itself. Can't be helped I suppose.
All in all, this was a decent launch title for the PS4. Not great by any means, but decent.