Australia is 3 movies in one. It starts as a slapstick comedy, becomes an action adventure and ends as a war romance. Add to that a precocious kid, mystical magic and the plight of the "lost generation" of Australia and it is a hopscotch of many things, but not exactly a good movie.
That said it looks beautiful, well shot and designed. And Hugh Jackman is gorgeous, take your breath away gorgeous. Unfortunately Nicole Kidman does not fare as well. She's too manic and brittle to be an enchanting romantic heroine. And the supporting characters come in two stock types, hissing villians and angelic good people.
Rent it anyway but see it over 3 evenings.