Out of all the Halo 3 maps, Guardian, Pit, Contruct and Narrows are epic. If you check out my stats on B.net, you'll see that i've played in the MLG playlist the most.
That playlists is specifically designed for hardcore Halo 3 players. Major League Gaming uses their own version of Guardian, The Pit, Construct, Narrows and 3 different maps forged on foundry....By "thier own versions" i definitely don't mean the geometry, but weapon and power-up placements.
Its really amazing that they've placed every weapon and every power-ups in its place for a reason. Teams need to fight each time a power weapon (rocket or sniper) or power-up (camo or overshield) spawn. Hence discouraging team camping and speed up the game as a result.
I play on MLG with a few friends in lahore and its definitely a blast.
People love Halo 3's Multiplayer for its fun....i love it for its competitive nature.