I just returned from a week paddling in the Florida Keys. While I read several paddling books covering the Keys before departing, the Atlas was by far the most useful. The detailed charts with suggested routes were great. Other books included routes, but the routes were often too short for a full day on the water and the charts lacked the detail needed to evaluate optional launch points, rest stops, side trips, etc. The Atlas also included detailed descriptions for outfitters, campgrounds, paddler friendly hotels, GPS waypoints, etc.
If you are going to spend some serious time paddling in the Keys and can only bring one book, the Atlas is the one to bring.