In general Black Ops has been a very buggy and poor experience. The single player story doesn't make any sense from start to finish, it's incoherent and actually discouraged me from playing the game.
Once you're in the game it doesn't really get any better. With the friendly AI randomly running off where they hell they like and without the enemy AI even firing a shot at them. Then you follow them thinking its safe to do so and get shot square in the head by an enemy standing next to (and ignoring) the friendlies.
I played the game to the end hoping upon hope that it would get better and the story would finally make sense. It didn't.
The Zombies mode is fun, but after a couple of hours play gets a bit boring. It doesn't help that there are only 2 maps to play. Lets face it though, if one wants to play a zombie game then I recommend playing Left 4 Dead.
Black Ops has a great little feature where you can break out of the chair and jump on a UNIX terminal. Here you can unlock goodies, the best of which being Dead Ops Arcade. A fun arcade top down style zombie shooter with powerups etc. Great fun and can be played with up to four co-op players.
The multiplayer is really good, especially with a group of good friends and a beer. They've taken it straight out of MW2 and tweaked it a bit. They've changed the way you gain new weapons, making you buy weapons and gadgets rather than getting them as you level up. This gives you a bit more freedom to what you get. You can then gain extra cash through contracts with objectives to attain. Overall an enjoyable experience.
The problem for me is, I get bored too easy with the small maps and once my friends go off the boil playing it... which they have now.
So back to Bad Company 2 for me! Vietnam DLC arriving at the end of the month :D