They work pretty well from what I've seen, I used to run a Detroit in my Montero and the Aussie works about like that.
PROS: Very reliable, Easy to install, Inexpensive
CONS: More effort to steer in 4WD, Increased CV wear, AWD becomes less useful
Just for giggles Air Locker
PROS: Selectable, Stronger than stock differential,
CONS: More involved install, Less reliable (Still pretty reliable), Expensive
Aussies are pretty nice.