My wife, 18-month-old son and I were able to get this book a few weeks before we left for a trip to Costa Rica, so I was able to compare information in this book to other information I found on-line, and to "on the ground" information once we were in Costa Rica.
I need to draw a VERY solid line before this review continues: If you're the type of person or group that feels comfortable with going to a new place and simply partaking of whatever "easily-accessible" activities or attractions there are, and not going too far off the beaten path, you'll have no problems with this book. If anything, this book will actually have more information than you actually need, so be sure you know what you expect from your trip before you simply read a travel book cover-to-cover.
That said, the only thing I can honestly say about this edition is that it's inconsistent. To be fair, Costa Rica feels a lot bigger than it is, and there are all sorts of awesome little things tucked away around the next corner, so there is NO way for someone to compile travel information that will cover every single type of traveler and every single slice of life in a country. With that in mind, this book does pretty well with giving you the general vibe/feel of an area, and tries to point out some good must-sees in just about every area.
Traveling with a toddler wasn't hard, but (not surprising) this book didn't cover that aspect. I really didn't expect that, though, as we're not exactly the target demographic of Costa Rica travelers (I'm guessing). As an aside: A LOT of friends and family asked us, "You're taking a TODDLER to COSTA RICA? Isn't that DANGEROUS?" To be honest, we felt more safe in Costa Rica than we did here in California. The book has some great safety/planning information, so that is a definite plus if you're not used to traveling in countries like Costa Rica.
Obviously, more popular places will have more information. Other super-awesome places that are off the beaten path won't even get a nod. The other problem is determining the starting-point for very subjective reviews: Some eateries we tried were recommended, but they were simply "gringo-style" Tico food, so we thought they weren't that good. Other eateries, however, barely got mentioned, and they were WONDERFUL. It's all about what you expect.
So. For an overall-vibe-get-to-know-Costa-Rica book, this is definitely a good start. When it comes to planning the perfect trip, however, you'll definitely need to diversify your sources.