My DH and I emigrated to Aus in 2007 and although there are downsides, on balance, I think it is a fantastic place to live and raise a family.
It is quite expensive and we are fortunate that my DH works in a well paid industry, but we have also chosen to live on the outskirts of Sydney, and I don't have to work.
Upsides to Oz - lots and lots of free outdoorsy things to do, wonderful parks, great beaches, children's playgrounds and BBQs all over the place. I can get through a week barely spending if I choose as there are so many great free things to do.
The people are friendly, welcoming, kind and generous.
The scenery is stunning.
We are skating along ok in an economic sense. people aren't spending too much but there is v low unemployment still and plenty of jobs.
Downsides - it's a bloody long and expensive trip back to the UK.
Snakes and spiders, big ants, leeches, ticks etc. If this bothers you, it's not fab (although we live on the edge of the bush, never saw any of these when we lived closer in, and I kind of like the quasi danger of it!)
Things are expensive like houses and food but only if you come from the UK, you're used to it when you're here.
The other things that have been raised - we do have seasons, they play football here and the bushfire risk around Sydney (and around the majority of the major cities) is really low. And you just have a bushfire plan, it's no drama at all.