One of the biggest problems with Halo 2's matchmaking system was that it didn't have a similar functionality for Custom games. If players wanted to play a particular map or a custom gametype and couldn't get enough people in the room, there was no way for players to find that game. It segregated Custom Games and Matchmade games, completely. In Halo 3, that's changing. While Matchmaking and Custom games are still completely separate (ranks will only increase in the confines of Bungie's matchmaking service), for players who just want to play Custom Games, Bungie has created XBL Public.

XBL Public is where players can advertise their custom games and then players will be able to seek out modes, maps and gametypes. If a player is looking for a Team Slayer match on High Ground, he'll be able to find the ones that are available and they'll be sorted by how good the connection to the match will be.

Source: 1up.com

Okay, WTF? This feature isn't even in Halo 3, and it pisses me off that I have to play a bunch of lame-ass games that matchmaking makes me play. I want a 16-player free-for-all Slayer, damn it! I don't wanna play the same damn maps over and over in matchmaking (seriously, I played on this one map 3 or 4 times in a row). No more random "Swords only" matches! >=[

Also, Halo 3 has the same VGA display problems on a 1280 x 1024 5:4 monitor that Gears of War had...man, WTF? Why is it that all these highly-anticipated games always have these small, but very annoying problems? Games like Dead Rising and Crackdown didn't have this problem. These games weren't super popular and highly-acclaimed, yet they could render an the game at 1280 x 720 and letterbox the image on a 1280 x 1024 monitor! But "GOTY material" games like Gears of War, Oblivion, and Crackdown don't support my monitor like they should (well, Gears EVENTUALLY did, after several months of waiting for a patch). This is pissing me off.