The multi-player in Gears is the main course for many, and unfortunately has been ruined.
The only problem that stayed with the sequel is the sound mixing. The voices sometimes get drowned out by either the music or the sound effects.
The multi-player is where the problem comes in. There has been a massive overhaul of the controls, interface and power of the weapons, most notably the shotgun, much to this games detriment. The best way I can describe what has happened is that they took everything I hate about Halo which is... everything, and put it into this game. I find the interface to be incredibly complex and aggravating. I can't choose the game type I want to play, it's basically a lottery, and if I want to play a quick match it takes upwards of ten minutes to find one if I'm by myself! In the old one you would select your game type, find a match, and join! Easy and fast.
They've also gimped the shotgun. That's supposedly to make it more "tactical" but it just makes it dumb and un-fun, and slow, and tedious. Before everyone would whip out their shotgun, and a match could be over in 5-10 minutes, and chances are you were having fun regardless of who was winning or losing.
The whole social aspect of it is completely gone, depending on what game type you're playing. For the classic Warzone game, you can only talk to, or hear anyone on the opposite team at the beginning or end of a match. That really bugs me. It's not like there were profound conversations going on or anything, but sometimes something interesting would come up.
Also, peoples ranks are displayed now. That doesn't seem like a big thing, but a lot of people take themselves way too seriously, and it just becomes less fun. It takes the fun out of the whole experience because you can't just enjoy playing the game for the sake of playing it. Sure people would talk down to others in the old game, but it was always fun to show'em what's what every now and then.
This is why Gears 2 is a waste of money. Goodnight.