Call of Duty Black Ops sucks?

I bought it today and I surprisingly find it worst than Modern Warfare 2. The problems with it that I find is the hit detection and how many bullets it takes to kill. It takes about 5+ bullets to kill. Sometimes I aim at some guy standing still and not all the bullets actually hit the guy. I regret buying CoD: Black Ops. I would rather rent a hooker for 5 minutes. Explain the problems you have with this game.