First of all, I love playing COD games, it's almost the only game I play nowadays. That being said here's what I see as the "bad" about this game:
First, the latency issues get really old in multiplayer, and whenever I'm selected as host, it's like I don't even have a chance against the opponents. I intentionally slowed my upload speed on MW3 because of this same issue, so I wouldnt get chosen as host as often. I really wish they could resolve the latency and hosting issues in one of these new game releases. I realize it will never be perfect since it's a game played over the internet, but there has to be a way to improve upon the current setup.
Secondly, Call of Duy in general needs to move away from leading players through campaigns and handicapping things in multiplayer, and the use of aim assist all together, so people that are terrible can play at an "equal" level. Video games, like all other games, sports, etc, are supposed to be challenging, and half the fun of multiplayer is competition. The fun of a campaign is making it challenging, so you have to figure things out, and strategize to complete a tough mission.
Lastly, the spawns can get pretty bad on this game, but that's nothing new really either. I think they try to make changes to the spawning system and sometimes it makes it even worse.
Here are the things I see as good about this game:
First, there's a good selection of maps for multiplayer with the initial relase, and the dynamic aspect makes them slightly more interesting than previous COD games. I always enjoyed how Treyarch included small dynamic features in their multiplayer maps, so it's nice to see from Infinity Ward this time around. I'm hopeful that the DLC content this year is great as well.
Secondly, I like that they tried to add some new game modes. I think of the new modes, Search and Rescue is my favorite, as it gives you a bit more of a chance than Search and Destroy does, and introduces another strategic aspect to the game. I also like Cranked, as that keeps people moving a little bit, and doesn't allow for as much camping.
Lastly, I like that they added some new killstreaks, I like the option of having the guard dog too, because it watches your back, gets martyr-dog kills, and gives you a warning growl when opponents are nearby.