Veteren is indeed very challenging. I thought it was harder than CoD4 campaign, but didn't have any "impossible" parts like CoD2 (convey ambush, AA gun, etc). Overall, I think I liked the single player campaign of CoD4 better, but I like the multiplayer in this one more. Zombie mode is pretty sweet too: I mean, who doesn't enjoy zapping zombie nazis with a 50's style ray gun?