Mexico is beautiful and I love it! A rich and diverse culture, beautiful scenery and architecture. Fascinating ruins of ancient cities and temples. Wonderful (spicy) food! I used to travel there a lot for work during the 90's. But even then it was getting dangerous, especially Mexico City. Right now things are politically tense due to the disputed election. You'd probably be fine, but one thing that made me uneasy in Mexico was the general consensus that, if anything did happen, the police weren't going to be much help. A co-worker was robbed of an expensive watch (which he shouldn't have been wearing, but he was careless) at an elegant cafe in a nice area of Mexico City. His Mexican colleages advised him not to call the police. "They'll just take whatever you have left".   It really depends on where you're going in Mexico. Mexico City has a lot to offer culturally but personally I'd avoid it due to the crime, congestion and pollution problems.

I don't know about Australia - never been there.