What should they fix for Gears 2?

Mutliplayer: Everything

Campaign: Nothing

sgpicker

i agree to the fullest, except maybe a little bit longer campaign 

Better graphic's

, you should be able to kill someone at the last second and then go save your buddy while the corpse of the guy about to stomp him topples over, foot still raised

RebornInFlames

you can shoot their head off with the sniper rifle before there foot goes down all the way

Multiplayer:  Pick up a weapon while running, also shooot while running, better hit detection and easier Sniper like Halo.

Campaign: Some more bosses and more interactive environments to defeat the bosses like RE 4 and God of War. 

Single player.....

Longer, more branching story

More use of Vehicles

4 Player CoOp on XBL

More Boss Fights...More Corpsers, Less Berzerkers

Multiplayer...

Eliminate host advantage

Make all attacks realtime and not animations...i.e. Curb Stomp and Chainsaw in their current state.

Up the teams to atleast 6 Vs. 6

Bigger Maps...Stuff like Gridlock, Raven Down and the like are too small.

More Weapons...SMG type gun, a Stun Gun or Tazer, maybe a flame thrower or Grenade Launcher

More game types... CTF, Territories, Assault, more respawn type games like in Halo. Who actually likes sitting and watching a match for 5 minutes? NOT ME!!!

Drop weapons that can be carried from 3 to 2 that way people will have to choose between Shotgun or Lancer  or whatever, but not both! Spawn with Nades.

singleplayer: the locusts side of the story, not just COG. I want to know why they attacked. I know it sounds like halo 2 but the locust was a huge part of the story, like how fenix's father had that huge blueprint of the locust tunnels....

Multiplayer: What makes GoW so fun is the multiplayer, and they really need to improve it. and for ranked matches we should be able to see if one of our friends are hosting/joined are in that room specificly rather than haveing to do 8 tries until you find them. that makes it far more easier for clan matches.

Weapons: Dagger- for one hit knockdowns.
                tear gas- to force enemies to evac from their hiding spots.
                Rail gun- One rail per ammo. one shot kill, can go through obsticles.
                tactical Lancer- a combined longshot and lancer to preform effective long range and deal out heavy damage.
                Dual pistol: Holding one of these bad boys was bad enough imagine pumping twice as much lead into the poor soul your fighting.
                Nitro granades- Explodes the moment it hits the ground so there is no chance for escape
                Inflammation Granades- Burn your foes straight to hell.
                Special locust/Cog only weapons. it adds more competition between the races than having the exactly the same weapons as the other race it just doesnt make sense...0_o

More weapons, dedicated servers, less sticky roadie run, make melees less powerful, MAKE THE BOOMSHOT NOT DOWN PEOPLE ANYMORE (the noobshot is the gayest weapon in the game it requires no skill), good single player, be able to invite friends to ranked matches, fix the glitches, client hit detection...

Those are a start.

also shooot while running, better hit detectionInjuredNoodle

Have you even played Gears of War?