Sydney is a beautiful city, but still part of a rather insular and inwards looking country. House prices are obscene (but are finally dropping!), the public transport is a disgrace compared to any European city, and if you work in tech, the really good jobs have only started to appear in the last 2 or 3 years.

I left it for Berlin, and mostly don't miss it (apart from days like today where I could perhaps tolerate weather slightly warmer thatn 0º.)