Having purchased the most recent iteration at the midnight release last week, it's fair to say that I was excited to play it. At first mention of it some months ago, I wasn't quite thrilled; but the more I read about it, the more I began to like it. That having been said, I preordered it after some sway and joined in the hype machine.
So far, it feels like a big improvement over Modern Warfare 2. If you've read my review on MW2, you'll recall that MW2 was a bit disappointing for me. Where MW2 featured every room full of bitches holding killstreak campfests, Black Ops discourages camping with a variety of design mechanisms - much to my delight. Also, the layout of the upgrading/unlocking scheme is a delight.
The shooting mechanics are largely unchanged from MW2 (And the first Call of Duty for that matter) which is fine. The slick and crisp shooting is a staple of the franchise, and has undoubtedly contributed to its success. Kills gained through killstreak bonuses add to the gross killcount for a game, but not to the immediate killstreak. For example, getting a kill with a bonus that requires eight kills does not grant the killstreak granted by nine consecutive kills. This encourages players to be active in the game, because they can't camp and hoard kills with devastating killstreaks. Needless to say, this is a positive change.
As much as Call of Duty players love to level up, some emphasis has been removed from it. Instead, CoD points are earned that are used to unlock perks, equipment and attachments - most of which are available from the get-go. Now, players engage in an economy of points instead of unlocking gear and perks at predetermined levels. I find this to be a superior layout, because I can accommodate to my particular tastes much sooner, letting me design classes to my liking as long as I spend my points wisely.
A full review ought to be around some time over break. So far, Black Ops is quite a mess of fun - as it ought to be.