Interesting to read all the comments in here. Like other people have noted, I enjoy reading people personal experiences rather than blunt opinions on aspects such as one country being backwards.
My personal story is that I arrived in Oz in 2010 as a backpacker with my wife. What was supposed to be a 6 month adventure has turned into a 6 year stay, so far. We were on the cusp of returning to the UK earlier this year, however unbelievable work opportunity for my wife has meant we are staying for the foreseeable future. In all honesty, if it wasn't for this we would probably have returned, however we have learnt to enjoy our life in Oz. Things I'm not so keen on are is the summer heat, for me personally anything over 30 is difficult to deal with, and the humidity in Sydney can get quite bad. Talking to older Australians they say this is something that has got worse over time. I miss English TV, the country side, pubs and generally being a very accessible country due to the size. Living in Australia there are very few places you can drive to at the weekend. Also, I find English people slightly friendlier, however I think living in Sydney is not a fair comparison - if you went to London you'd think all English people are miserable.
I do wince when I hear stories of people selling up and moving here, having never visited, especially to either Melbourne and Sydney. In the 6 years we have been here house prices have risen astronomically and due to massive tax breaks for investors I can't see that changing any time soon. It's also very difficult to live outside of Sydney in a more affordable area and commute in due to poor public transport. For example, living in the central coast 40 miles north of Sydney will be a 2 hour commute into the city. We rent 5 minutes walk from the beach in the southern suburbs, if we wanted to buy it would have to be somewhere in the sprawling west of Sydney, even then a three bed modest house would cost nearly $1 million - and it really isn't the postcard Australia.
In reality, unless you have a specific trade or occupation it's very hard to get out of either Sydney or Melbourne, I think that is where the UK has a massive plus over Australia. The abilty to live in smaller towns and cities and commute.