A team at the after PAX shindig tried Legendary, after a long romp on Heroic. They were cocky. And didn't get past the first round. And holing up in some corner of the map - like the spawn area - doesn't work. The enemy comes in too fast, and with Catch turned on being in a corner is a bad place to be. And with Tilt turned on, you can't hide in the spawn room, which only has SMGs and pistols. You gotta go get the plasma weapons.
I'm still not sure how the bonuses work. I actually thought there was one for clearing rounds quickly.