First off, make note that neither of the other two 5 star reviews (at the time of this writing) are actually for this book. The book doesn't rate the different camp grounds and contains little information that would help you in deciding which ones to visit. For each campground, the author provides information, including directions to the campground, the number of RV and tents sites, the cost, and a brief paragraph giving the highlights of the campground (mostly descriptions of activities available rather than characteristics of the camp sites themselves). I doubt that there's more information here than you could find on Georgia's Parks website.
Get "The Best in Tent Camping - Georgia" instead. Although I don't completely agree with all of the author's rating of the campgrounds that I've visited so far, it's far better book. It's clear that the author of the latter has at least visited the campgrounds being described. It's not clear that's the case with "Camping Georgia".