It seems Gears 2 for the Xbox 360 is sliding down the list like a little kid in a sled in aspen. This could correlate with the time you have to wait to get in a dang match.
I know I have not played it in some time because of that reason. The patch Epic and Microsoft released was supposed to help but, it helped only a little bit. There is no lag issues or anything like that. Its just the matchmaking system they have. I have noticed that in horde mode I have no problem finding a match.
If you want to play anything else like meatshield or warzone forget it. Unless you have 5 to 10 minutes to spare waiting for a match. Well i hope they figure this out to bring back the playability that I loved in Gears 1.