Ok, I bought the PC version because my old clan friends said to so I could rejoin them.
From playing for about 4 hours I have to say its not all that it is cracked up to be.
The game feels kind of slow but fast at the same time. Killzone 2 is a better FPS which is sad coming from a PC fanboy like myself. Normally PC > Console games.
It is not a bad game its just not that great.
I have recently reinstalled Battlefield 1942: Desert Combat mod and will boldly state that there is no comparison between the two games. BF1942:DC is a better game even though it was released a decade before.
Truthfully I have never been a COD fan because the games always have the same gameplay feel but COD4 is better than the res.
In my ranks of PC FPSs I truthfully put COD4 towards the bottom in terms of gameplay and qualityt.