My husband and I were going to Costa Rica for our honeymoon so, wanting to research it thoroughly, I bought 6 different C.R. travel books. I bought this one last and wish I had bought it first. It was the book I kept going back to. It also had the most useful maps of any of the C.R. books I saw. We wanted to stay at a mix of regularly priced places ($100+/night) along with the occasional splurge of $200+/night places. We also wanted to stay at enviromentally-friendly places as much as posible. This book got the job done.
CR for Dummies is the best intro/overview book. I would also recommend buying The New Key to Costa Rica because it has more detailed information about accomodations for all budget types and lots of additional info on activities and tours that you won't find in Dummies.