Here's a set of pictures of New Orleans’ Lower Ninth Ward that I took on January 5. I'd guesstimate that 12-16 blocks are just gone. Many more are 70% rubble, 30% collapsed houses.
As you'd expect, the further away you get from the breaches and the higher the ground, the better off the houses. You see a similar, if more glaring effect on the Mississippi Gulf Coast. There, if you drive north from the beach, everything for three blocks is gone; then, on the next block, suddenly everything is standing but damaged by wind and trees. But New Orleans lost approximately eight times as many homes as the Gulf Coast.
More photos at
realitique.