Well, I played War Rock today and the graphics suck pretty bad. =P Some nice features yeah, but less hackers? You could say that in some kind of a way. Combat Arms is filled with "Stealth" hackers, they cham, no recoil and all that stuff.
But in War Rock, it's a different story, no one is putting limits on V.I.P. hacks and Public hacks. V.I.P. hacks are released publicly and everyone is using them. About one week ago before the patch, in every single game, there was an OPK hacker. Now it just got a little better, but still there is still a considerable number of hackers, but due to the fact that War Rock is less popular than Combat Arms. Well yeah, you could say that there are less hackers in there.
Still, I would stick to Combat Arms, after the 4th of February patch, everything will be going nice and smooth. (I hope so.) Also, I own pretty much in War Rock. =D If you still want to join War Rock, my IGN is: vdarklinkv.