This is a very good guide for an area with an incredible array of species. Besides Costa Rica, none of the other Central American countries have a usable guide in the field so this could come in quite handy in Panama or Mexico for instance which have large, informative, but quite cumbersome guides of their own. This guide easily slips into your pocket and illustrates all the species you may see over a wide area. Range maps are also easy to reference based on the bird's number on a particular plate.
The illustrations in this guide are comparable to the Garrigues guide for Costa Rica, and in my opinion better than those in Stiles & Skutch- although they are smaller in this guide by Van Perlo and sometimes bunched up on the plate. The illustrations remind me a bit of the Sibley guide-sketchlike but proportionately very accurate.
I would give this five stars for fieldworthiness but way too many plates have birds whose names appear on a different page making it very hard to compare certain groups of birds. I don't know why they only went with 96 plates for this book when Birds of Western and Central Africa by the same company has 109 plates for fewer species.
This book contains the same material as the Princeton Illustrated Checklist for Birds of Mexico and Central America but has a nicer cover and cool glossy paper. If you are taking this book out of the home library and out into the field, I don't know if the glossy paper is a help or a hindrance :)