yeah well ive downloaded them and played them. here's the facts. (some would call them my opinions, but since im always right, facts will suffice.)
1. Containment - Definitely the largest and shittiest of the bunch. Not a surprise. Bronson was joking about how one of the bases was probably bigger than midship. Shitdamn, he was right! I hate to say this, considering I hate vehicle noobs, but if bungie doesn't put more vehicles in there for BTB, it's gonna blow even harder. It's so damn huge, it'd take the whole match to traverse it. So the only way you'll actually see someone to shoot at is to have a 16 player match with BR spawns. Doesn't matter since the game will be so laggy you'll tear your eyes out and slit your wrist for downloading this shitty map.
2. Warlock - Nice and simple. I personally can't wait to play MLG TS (2 on 2s baby!) on it. There are 4 br's on every platform so that should keep the dual-wielding noobs away. Ball matches would also be pretty cool on it.
3. Sanctuary - I like the way it's set up. MLG CTF-Midship would be fun on it. It's not that huge, but not too small. There is, however, an ungodly amount of rocks in the way that totally omits vehicles. I'd actually welcome it just to see a full warthog of noobs smash into a rock while I proceed to get a triple kill with a sniper rifle. It'll be pretty cool, but matchmaking with smg's will be meh.
4. Turf - My SWEET god. Camper's Paradise. This is gonna be gay. It reminds me of cs-italy on CS. There are so many alley ways and boxes for people to hide behind. I can totally see my self running along just to get assasinated/plasma rifle-smg'd while i'm trying to have fun. This map=crap.
I suppose turf would be ok under the right conditions, but containment is total suckage. Sanctuary and Warlock will be nice for mlg, but it won't matter because the matchmaking options bungie provides will undoubtedly suck balls!