I think the biggest issue with this game is the skilled based matchmaking in public lobbies and it should be the top priotiry complaint and most discussed topic in here and twitter for treyarch and activision to hear.
Because of skill base matchmaking most of you are experiencing lag issues. It is putting you into lobbies with players at great distance to you because of skill and not locale. This in turns creates the huge lag comp topic or why do i only get 2 bars every game.
it also in turns gives us most of the complaints as to why you die so fast or get killed by 2 bullets from a pistol or smg at distance. It is the lobby you are in and not so much the games mecahnics. Again lag.
You are now forced to go tryhard every game because you are only playing with equally matched players. Same tactics usually and same stats. This makes the game very unpopular and less playable over time. One of the huge draws to playing COD and putting the time in was to rank up, Get good Kill streaks and to have games where you dominate. This game makes it more like halo now. Not a bad thing, i do like my occasional skilled games but in public in halo it is not by skill. This is what we have leauge for now isnt it?
The other problem with all of this skill system is also parties. If you have a party leader who is a beast, then you are forced to play on his level. The game searches for lobbies on his skill level and not the parties. Some of you may say good! Because you have friends with horrible stats. But some of us are the low man on the pole and your friends are running 2.00+ K/D's or average 800 SPM in most games. This will make for some very depressing games.
There is more to talk about on this issue but i dont feel like typing for 3 hours.