There is vigorous debate on the north island of Australia about the relative merits of boots and lightweight sandshoes. It seems to be a bit religious actually. There is less debate in Tasmania, and a more general acceptance of the need for boots of some sort in many circumstances.

I recommend strong shoes or boots for most walking, but that's what suits me. If you want to walk in Dunlop Volleys, and they suit your feet, go for it.

Boots have the advantage of strength, and will protect your foot/ankles on rough ground. They also slow down the flow of water around your foot in wet conditions. Most will not be guaranteed to keep your foot dry, although some of the later Gore-Tex lined boots are reported to be pretty good unless the water's deeper than the boot. In this case, they also keep water IN the boot very well, like a wetsuit.

Most boots do still need to be worn in somewhat, some more than others. Even the lightweight cloth/mesh/leather boots will need to be trained to fit around your foot before you venture a long way off the road. Carry blister pads when wearing in new boots. Boots are also heavier than sandshoes, although some of the lighter ones aren't much different. Really there's a continuum between sandshoes and boots these days. Just try looking round the shops.

Sandshoes have the advantage of being light and comfortable. Just be aware of how rough, wet, muddy your walk is going to be. Some people's feet are better off in boots in many circumstances. Also, you may find that bushwalking, especially carrying an unaccustomed weight may lead to blisters where they hadn't formed before.

See the whole catastrophe on this subject at the Bushwalking FAQ footwear section.