Under cons, it says that voters have to rank all candidates on the ballot paper.
In reality you have a choice. You can either rank all, or if you are lazier you can just select your favourite candidate and then your first choice candidate's preferences will be used instead.
Also for some larger ballots (usually the senate with nearly 100 options) there is now a requirement to only rank say the top 10 or so for the ballot to count, so you don't need to number all 100.
This is one of the best features of the Australian system. If you want to do the basic effort you can just tick one box, but if you care about the ordering you can also make your preferences count if you so choose.
As an outsider looking in to American politics, I feel changing to preferential voting is the best bang for buck change to move away from extreme politics. Hopefully this catches on elsewhere.