I should start by saying that I travel extensively and plan all my own trips. I enjoy the planning process almost as much as the trips themselves (sometimes more so, after a rainy trip to Switzerland when we did NOT see the Alps even once!!!). I've used countless guidebooks and internet sites, and consider myself pretty knowledgeable on travel information sources.
I bought this book as a starting point for planning a trip to Costa Rica and while it contains an incredible amount of information, I felt like it was too encyclopedic to be easily helpful for planning. For example, the first 170 pages deal with history, culture, national holidays, wildlife, etc., etc., etc. While I think all of this info is valuable and interesting, I don't want or need most of it when trying to decide where to travel within the country. This book, while providing a ton of detailed information, seems to assume that the reader has some previous knowledge of the country regarding possible itineraries and what the 'must see' areas are. Its 'Suggested Itineraries' section is one paragraph long and basically says 'do what you want and can afford' - not a big help, in my opinion. I don't always follow suggested itineraries but I find them helpful as a starting point, especially in a country as diverse and filled with so many wonderful possibilities as Costa Rica.
Additionally, I found the format to be kind of like a laundry list - lots of stuff but often no indication of relative merits between lodgings, attractions, etc.
I ended up going to the library and using Frommer's and Fodor's as a start for itinerary ideas and then used "Rum and Reggae's" Costa Rica (Jonathan Runge & Adam Carter) as a good source with a definite 'point of view' and lots of opinions. They make pretty clear WHY they like or dislike something, which helps determine if I'll agree or not.
Having said all of this, now that I've planned my trip (using other sources), I will read this book more closely and I'm sure I will benefit from it. It IS an exhaustive (and perhaps exhausting!) source of, I'm sure, everything you've ever wanted to know about Costa Rica.