When I first visited Australia (2005), I went to a bookshop in Sydney and looked through all the available field guides in order to make a selection. One book rose to the top: the seventh edition of Simpson and Day’s field guide, published in the United States as Birds of Australia: Seventh Edition (Princeton Field Guides) (ISBN 978-0-691-12049-2), in the UK as Field Guide to the Birds of Australia (Helm Field Guides) (ISBN 978-0-7136-6982-4), and in Australia as Field Guide to the Birds of Australia (ISBN 978-0-670-04180-0).
I liked the illustrations better than the ones I saw in the other guides (though unfortunately I didn’t make note of which guides I was comparing it with at the time). The organization is nice too; illustrations, species accounts, and maps are generally located on the same two-page spread for each species. Maps show seasonal movements and distribution of subspecies/races. Species accounts are terse but contain ID pointers, length in centimeters, habitat info, voice descriptions, and black-and-white line drawings to illustrate young birds, anatomical features, etc.
In the back is a section illustrating 70+ vagrants and another section containing info about nesting seasons and habits. There are also checklists for Australia’s widely scattered island territories. Though these island birds are listed in the back, they are not all covered in the guide itself.
Simpson and Day is one of four main Australian field guides. Different birders prefer different guides, and many suggest that owning two or more guides is helpful. I’m sure this is true. For now, I’m happy with Simpson and Day. If I return to spend significant time in the country, or if I visit some of the remote island territories, I will look into obtaining a second guide.