NOT FLAMEBAIT, lets be clear on that right now, so put away your pitchforks xbots.
1) COOP LUNACY
If anyone leaves the game, either via manual leaving, xbox 360 crashing, or internet disconnection, *EVERYONE* including the host, is booted back to the lobby, this gets especially annouying when you consider up to 4 people at any given time can be around and possibly quit on your ass.
2) LAGTASTIC BOOMBASTIC
4 Player online coop, lags, like, a , fothermucker.
And not just jerky movement lag either, the controller decides to start lagging ALL your input locally, so everything you press can be from half a second, to 3 seconds slow to actually do what you press on the screen.
"One two miss a few ninty nine one hundred"
Seriously, what is the point in that loading bar?, no matter what, on every level it basically counts from one to 20 then surges to 100.
4) Oh hi i fixed ur weapon
Starting a level online, without a weapon equiped, even if you had one in your hands when you completed the previous level, what the **** is that ****?
5) Oh hey guys i know we're half way through the map but a guy i know wants to join
Really, not being able to join in the middle of coop matches is real fail, and not being able to leave without killing the game for everyone else is real fail also, it is something that needs to be urgently addressed, as it completely ruins the coops ability to be fun.