I do not understand Bungie's reasoning behind the way they do playlists.
I realize that Reach has 32984209348243 game modes, making individual gamemode playlists somewhat problematic, but there's no reason they can't bundle off certain similar game modes into one playlist (SWAT, Pro, Snipers), and put silly fun stuff in another (Infection, Rocket Race), while still leaving some core 'big' playlists (Team Slayer, CTF, Territories, Invasion, etc)
Voting doesn't really help, if the majority of the playerbase enjoys a mode you don't, you're fucked son (bring a big party, or have fun in SWAT!)
But having these 'grab bag' playlists with a mishmash of modes is just irritating, and when they punish you harshly for quitting (and betrayals!), it's a pretty hostile playground for relaxing with what you want to play, when you have the time to play it.
I lost a lot of friends in Halo 3 to Shotgun/Snipers et al, they simply went and played CoD4 (or now MW2->BO), where they can pick exactly the mode they want to play.
I'm actually avoiding pushing the MP too hard right now to my friends who are lukewarm about Halo in general, since I'm expecting that the more egregious issues will be sorted out (betrayal booting, SWAT/etc in team slayer).
Out of all MP fps games with matchmaking, Halo is the one game with a large enough fanbase that they can _afford_ the discrete segregation of their playerbase into a variety of distinct playlists, but instead they use mixup hoppers and voting. Baffling.