Aussie lockers are good for what they are...
Cons:
Icy or rainy conditions are gonna be more difficult to handle, you will have slighty greater rear tire wear, very tight turns will be more difficult on trails, and you will have to get used to that ratcheting noise. You cannot run it under power unlocked, as it locks at all timew when you are on the gas. That being said, your driving style will quickly adapt to the new setup.
Pros:
Cheap. The most bang for the buck on the market. You will just walk right up stuff you used to struggle with. You will never have to "switch" to off road mode as far as your drivetrain is concerned. You will always be ready to go (except airing down). These lockers are also very simple, with little that can go wrong with the workings.