Old thread, I know, but wanted to say this game disappointed me. I didn't find the single player as enthralling as MW2 - it seemed abstract to me, like it was a story created for the levels they had built. And the way they were extracting information from you made no sense considering what was going on.
Online play I thought took a step back as well. The physics were improved, but the maps felt more like a paintball arena. Takes stealth totally out of the equation. I could see the map setup being more fun if you truly played with an organized team, but to just logon and start going, frustrating. It's just run and gun and hope you die less than everyone else. My favorite online play was World at War. The maps were so different, each one offered something unique yet almost all allowed for various tactics. In both MW2 and Black Ops, I have trouble finding a purpose for any weapon other than a good assault rifle. Oh, and having a 3shot M16 is a head-scratcher when 3 bullets sometimes won't put an enemy down (until you level up).
So enjoyable, but overall disappointing. I was hoping for more.