COD4 didn't have lag comp.
Yes it did, it just wasn't geared to allow those with shitty connections to play well. It was designed to try and keep hitboxes in sync with character models. That's why CoD4 lag ALWAYS caused frame skips and frame rate drops.
CoD4 meant you had an advantage if you had good internet vs. bad internet.
Since CoD4 Activision has geared lag comp to make the game more even among the overall player base. Meaning retards with no port-forwarding on routers, running on Wifi, running on DSL and other shit-level internet don't get boned by running CoD that way.
This has meant that those who know what they are doing, and port-forward on their routers, or plug directly into their Xbox, and have good internet are now playing like they're in the group from the paragraph above.
This is because it means more people will play the game, because more people have shitty internet and belong in paragraph #1 than #2. This means more money which at the end of the day, is all Activision gives a shit about.
This is why the game can look like it's playing fine, but the hitboxes and character models can be entirely separate. It's why bullets constantly zip around corners and break the laws of physics, because MW2 and on are playing more and more on a time spread between players.
Even though Black Ops 2's biggest problem right now is lag and match-making, there's still huge issues it would have to iron out to be good IMO.
The B23R is entirely OP if you have good hit detection, I haven't even tried the KAP40 but the B23R is stronger than the MW2 Raffica, and that's just absurd.
UAV spam and Ghost are not balanced, because this game will literally balance on how many Ghost users one team has vs. the other and how fast they shoot down UAV's and Counter UAV's. The longer killstreaks are not generally viable as lag is so bad (atleast on Xbox, with port forwards, good internet, open NAT, and best match search preferences).
The high killstreaks chain like mofo's, especially if you have Hardline. Hardline + Warthog = Lodestar/Gunship = Dogs/Swarm.
The perk system is total shit, as is the unlock system.
Basically players will prestige and carry over Ghost, then just run around with silenced SMG's, or move from headglitch to headglitch doing the WoR wobble to avoid UAV detection.
^ looking forward to that let me tell you
The maps are built for bullshit. Headglitches every ****ing 5 feet, punishing any sort of aggressive rush play by faggots sitting behind everything. There's not even corner camping that much anymore, because there's ideal headglitches on literally every point on every map.
It pays to be a camper, provided you have Ghost and a Silencer and keep moving a bit, or shoot down UAV's. Of course, that means you have to be somewhere you can get kills too, which can be impossible on some maps because of the retarded design and spawns like Hijacked (the Yacht level).