At this point seven years ago, Katrina was packing 182MPH winds. "Barometric readings lower than the worst storms in modern history. Cat 5 is >155, IIRC. If they had a Category 6, Katrina would be in it, heading for Cat 7."
At the last report 11 minutes ago, Isaac is not even up to hurricane status, packing only 70MPH winds. It is heading to the Big Easy almost seven years to the day after Katrina, but is no where near the monster of his older sister.
That being said, even a garden-variety Cat-1 hurricane can bring lots of damage; A Swamp People episode is bound to come out of this and a new governor in MS gets to test his mettle like Gov. Barbour did seven years ago. However, LA is the ground zero, and Bobby Jindal will have the bar set high after being a bit too ready for Gustav.