Apart from its graphics, what exactly was overhyped about Killzone 2? Not that many people claimed it would have the best gameplay evah, only that it was a very good FPS, a claim it has lived up to.
I dunno - maybe we're using different definitions of 'overhyped'. People making a lot of threads and talking about it a lot isn't the same as 'overhype' for me - it just shows that people are excited for it, and want to talk about it.
I consider 'overhype' to be people blowing aspects of its out of proportion (such as claiming that Killzone 2's graphics are better than Crysis', for example, something that clearly isn't true).
And as I said, I don't think any aspect - other than the graphics - have really been overhyped.