Ok, i am disappointed game on PS3/X360/PC -> "Call of Duty: Black Ops"
I beat this game on highest difficulty setting -> Veteran...
Every next mission was little harder... but... last mission was easier than first level in "Call of Duty: World at War" !!!
Call of Duty: World at War, i beat on Veteran too, but that was very frustrating and a lot of dies, tries, tears and blood

That was not easy! I remember that when i beat one level, i thought this is Wonder, now i do not know hardest level in this game, every mission was ver hard to beat on Veteran... especially on gamepad (X360)... but after I beat both games on Veteran difficulty settings, I am happy now

I should add, that i beat both games in single player campaign mode, both on X360.
You should try, You can die in first mission a lot of times in World at War: "Hi player, what You think about die here 30 times? Before you reach next checkpoint."