black ops was mediocre to me. Most call of duty feels the same but I am looking forward to modern warfare 3 , Hopefully it's better than black ops since I lost interest in that game pretty quickly.
I've always though call of duty 2 was the best one. after call of duty 4 they just like putting you in a room and sending too many guys your way. you end up cowering behind a desk. the firefights are too intense. it really has changed multiplayer forever tho, soo many new games copy their ideas now. the trouble is I feel like I've done their gameplay to death now.
I liked the single player, I played through it once. I played the multiplayer about twenty levels until I realized it was the same shit I got bored with in MW2, so I sold it to my friend who wanted it. He likes it (even still plays it) so it was a win-win situation for both of us.