Well.
You get better quality food.
You get more sun.
You get more space.
The standard of living is better.
The girls are gorgeous (if you're allowed to look).
You can get a "Ute" with a V8 (I would).
But it is not England.
Seriously though, I have a friend who emigrated (chasing after a girl) and he doesn't like it. He says too many of the people are rednecks, and they have draconian Internet censorship laws, draconian car modification laws, draconian speeding laws (more so than the UK!), and a government that manages to be more inept than ours.
Personally I found Melbourne (we're I've spent the most time) to be too much of "little USA" for my taste but that was just visiting for a couple of weeks.
Also I'm struggling to think of any Australian intellectual innovation, but most people probably wouldn't care.
Guess the best thing to do is investigate and spend a couple of weeks there if you can and speak to others who have done the "prisoner's move".
...I'd still buy a V8-powered Ute. Holden or Ford, either'll do me. Put a rollbar and some spotlights on it and roll around with a posse in the sun chasing girls.