Unfortunately this book doesn't live up to its potential.
The most obvious shortfall is a lamentable lack of colour plates. This has been well documented in other reviews, but it really does restrict use in the field.
Imagine the scenario. You are wandering along a beach somewhere in Tobago, and you see what is obviosly a member of the tanager family, so you refer to this volume. There is no illustration of the bird you are looking at, so you have to refer to the text. You go for the most obvious entry, only to find a description along the lines of 'very similar to species a) with the exception of...', so you refer to species a), only to find no correlation with the bird in front of you. By the time you've finished this process the bird has returned to it's summer feeding grounds in Costa Rica and your chances have gone.
Sorry to be so negative, but I've recently attempted this very exercise, with immense frustration. I still have several photographs that I'm unable to positively identify with the aid of this book.
Other reviewers have criticised the plates, but lauded the text. I would criticise even the text. Since when has a Southern Lapwing had a black bill? (no plate available for comparison).