We've spent three years in total in Oz and NZ at various stages (we're both medics) - pre-family, and post-DC's. We love both countries, and constantly wonder about going back - but right now there are NO JOBS for DH (though plenty for me in GP/pall care). He's the main breadwinner though, so I am trawling through the job ads on a weekly basis on his behalf.
I would say that work itself is not hugely different - in fact a lot of the Aussie docs we knew were pretty serious and hard-working and pale and academic! Though there were notorious exceptions of the surfy variety of course
But what IS different is leisure time, of course - all that fabulous sunshine and all those gorgeous parks/beaches/outdoor activities
Money - well, it's very good in places like WA - doctors in Perth seem to be rolling in it, from what we saw. It's less good in NSW, better in QLD (I may be out of date here, but that's how it was a few years ago). It's much less good in NZ - but the amazing scenery there makes up for a lot.
We know several people who've taken the decision to stay and are very happy. We chose to return to the UK for the usual reasons of family and friends, and proximity to Europe. But we're feeling the pull of the Antipodes again right now - mind you, every winter I vow to leave the UK forever, then soften towards it in the Spring!
I have looked into Canada but it looks quite difficult right now to get in unless you're prepared to work and live in Saskatchewan (sp?) or similar - plus we're heat-seekers rather than cold-lovers!