Joseph Forshaw is a highly experienced Australian ornithologist, and is widely recognised as an authority on the world's parrots. He has written a number of previous books with similar titles over the past few decades (most recently in 2006). The present volume is an attractive, well-produced book in the style of a field guide, published by Princeton University Press as part of the Princeton Field Guide series (and as a Helm Field Guide by A&C Black). I have to admit at the outset that I don't really have the expertise to search for errors, having only seen a tiny proportion of the species included, but on a quick check through nothing obvious leapt out and I suspect there will be very few indeed.
The introductory section is extremely brief, but a helpful and clearly authoritative synopsis of a number of subject areas relating to parrots, not least conservation where the author acknowledges the problems with collecting for the cage-bird trade but points out that the issue is often secondary to the more serious issue of widescale habitat destruction.
The majority of the book is taken up with the species accounts, with the familiar format of colour plates opposite brief notes on identification, similar species, distribution and subspecies. Of interest to the budding world-lister, most species also have a small number of recommended localities listed. Maps also presented for each species; these are clear and notably they often pick out the subspecies distribution by effective use of colours on the maps. The text is somewhat brief, as typical for this type of book (and there are certainly other books available if you need a greater level of detail). Detailed consideration of "similar species" tends to be restricted to sympatric species only, which is fine is you are using the book in the field, but is less helpful if you want to use the book to identify birds in (or escaped from) the cagebird trade.
The plates are very clear. As well as perched birds, many species are also depicted in flight, often both from above and below, which will be extremely useful for field identification. Similarly, the inclusion of many of the more distinct subspecies is also very welcome. Flicking through the plates, some look a little garish but on reflection, this is the fault of the birds and not the artist!
So, the book is a good one. I guess my only question is about the book's purpose. The author says that the book "is designed primarily for use in the field". It is certainly of field guide size and style, but I admit to being confused as to why a birdwatcher or ornithologist would really want to take a book into the field that contained all of the world's species of a single group of birds. Would you then also need to take "Raptors of the World", "Ducks of the World", etc?! It would make for a fairly heavy set of luggage, and I suspect most people would rather stick with the usual approach of a book covering all of the species to be found in the geographic area being visited.
However, this minor quibble certainly does not detract from the value and quality of the book, and if you want a good reference to this ever-fascinating group of birds then I would certainly recommend it strongly.