The more I think about it, the worse this game is.
1.The lag compensation and netcode in general-
I can't tell you the number of times I've had a party break up in this game. I seriously can't. There's the whole matchmaking bug where it looks to balance teams as well but that'll probably get fixed. Then we have matches where everybody and I mean everybody has a red bar and the games are unplayable. I've had that happen five or so times and holy fuck is it frustrating. Then there is the lag compensation. I personally haven't had too bad time because of it but I can definitely tell it's there and it's annoying due to the spamming of the SMGs.
2.The Maps-
They're as a whole, not as bad as MW3 but they're not much better either. All of them are pretty much CQC meaning the SMGs have an ungodly advantage over pretty much everything. I'm not opposed to multiple entrances for a spot so that's fine, however the amount of headglitching in this game is insane. There are maps where you literally have chokepoints full of headglitching, case in point being Slums. Also since the maps are so damn small, they make Objective based games, explosion heaven. Domination is close to near constant explosions going off in the background.
3.The Quickscoping-
Somehow this is worse than ever. Even in MW2 or MW3, it wasn't that bad or prevalent. It's mostly due to the whole OHK for any bodypart from a sniper making them godawful.
4.Weapon Balancing-
The SMGs are king. Yes there are times when the ARs can be useful but in general, you will get rushed and you better pray you have a SMG. The firing rate, accuracy, lack of recoil, and damage make them ridiculously good compared to the other classes. No other COD was ever this bad and it truly has become a spray and pray game.
5.Scorestreaks-
I like the concept of them but they made the higher streaks way too inaccessible. There will probably be a handful of people that will ever call in the dogs legit or get the swarm without a carepackage. That poses a problem as nobody will bother trying and just stick to the lower streaks which means you have a plethora of UVAs everywhere as nobody is going to take a risk on getting some insane number of kills in a row, especially when the points per kill are reduced in objective type games.
6.The Unlock System-
Ghost being level 55 is bullshit and highly biased against lower ranked players. It seems they did it to avoid camping but people used it in legit ways for flanking and this really fucked over a lot of people. It's insanely stupid. The rest of the system is a complete step down from Black Ops 1 which let you do what you want, when you wanted to.
7.Spawn System-
COD has never had a great spawn system but this is probably the worst of them all, even of MW3. There have been times when people have spawned 10 feet in front of me and I shot them in the back. I've never seen it this blatant before. It's a complete mess and on certain gametypes such as Hardpoint, it becomes a gigantic clusterfuck because the game doesn't know how to handle spawning people away from the action and not directly in someone's line of sight.
In short, the multiplayer is the worst since MW2 and MW2 only takes the lead because of the exploits and glitches. Many of the above have been problems in prior COD games but it's worse than ever in BO2.