First and foremost, the fact that killstreaks do not chain together greatly reduces the chaos and, at least for myself, puts more emphasis on just playing the game instead of aiming for the next killstreak. The exploding RC car is quite common as it only takes three kills to earn, but it's pretty easy to hear coming. The few times I've been subject to going up against the dogs or a chopper gunner, it's been tough to deal with, but it's incredibly rare so far.
As for the guns, I was saddened to find that kitting yourself out with Lightweight, Marathon, and Steady Aim (or similar) along with a sub-machine gun or shotgun still makes for easy kills by sprinting around the map as fast as possible and killing whoever you come upon. It's just not my style of play and makes me miss the development of frontlines, which happens when people use mid- to long-range weaponry. That's just my style, though.
I'm still making my way through the weapon unlocks, but found that the initial assault rifles (my favorite) are particularly weak. The M16, one of the best weapons in previous games, sometimes takes two to three full bursts to drop an enemy. At the same time, it seems like I often die to a few rounds from a supposedly weaker sub-machine gun. Killcams are still janky, which can make it difficult to figure out why I died. I'll hit an enemy a few times, die, and see that from his perspective that none of my shots actually landed (or I didn't even fire according to the server).
I like the use of CoD Points for unlocks, especially since they aren't available for purchase with real money! It takes a little bit to get used to the fact that everything will cost points and that challenges no longer unlock weapon attachments. I'm able to unlock what I want to use immediately, which is great, but it doesn't really encourage a variety of playstyles. Wager matches are fun, but don't really offer much of a return on investment at the lowest levels. This game is all about min-maxing your time to unlock and earn as much as possible as quickly as possible.
The maps are great, but a few gametype and map combinations can lead to some massive headaches with spawn camping. Domination on Nuketown, I'm looking at you! On the frontend side, Treyarch has done an amazing job adding features to the game for replays, leaderboards, customization, friend management, and (on the Xbox 360) disabling party chat in certain game modes, which could be used for cheating in MW2.
Black Ops multiplayer is definitely in between Call of Duty 4: Modern Warfare and Modern Warfare 2. It takes most of the gameplay innovations from MW2's system, but tones it down so it isn't just a massive killstreak spamfest. Besides Wager matches, there isn't a lot of "new" content, but the overall package is definitely more functional and enjoyable than Infinity Ward's latest.
Be sure to read Garnett's Black Ops review for his full impressions on the game's campaign, co-op zombies, and multiplayer.
is there no coop in the campaign? :(
Zombie mode is the only game mode that has coop.
No co-op campaign... I was sorely disappointed in this removal by Treyarch. Overall, the game is still better than MW2 in my opinion. I haven't seen any lag or problems with connecting on 360, besides when trying to join a friend's party game.