Eh, not fucking things up in the way that seems to happen in the states. Our conservative government is much more corporate oriented and less strong on climate policy, but they aren't insane. They don't tend to strip rights from women, and almost the entire party supported gay marriage legalisation with many openly stating they personally disagreed with it but understood that their constituents needs should come before their own opinions.

Edit: I guess to expand upon my point, mandatory voting means candidates need to run on a platform which considers the needs of the whole population. Optional voting means that if 50% of the population doesn't turn up, and 30% of the remaining population feels very strongly about an extreme view, it becomes easier for that extreme view to win an election.