If I had to pick a single book for planning a trip to Yellowstone and the Tetons, I'd recommend this one. It has enough information to get you started about any activity you like: backpacking, biking, boating, camping, fishing, hiking, horseback riding, mountaineering and rock climbing, and winter sports. You'll want another book for the more involved of these activities--especially backpacking, mountaineering and rock climbing--but you probably already knew that.
If you're on a family vacation, the book is near indispensable. There is good coverage of a nice range of day hikes. It's also exhaustive in telling you the other opportunities available that you might not have thought of by yourself. Rafting down the Snake or biking on the valley floor of Jackson Hole are two good family activities.
There's also plenty of information here about regulations, places to stay and eat, and suggestions for other excursions in the area. The written material (but not the maps, alas) is organized very effectively into regions that really do follow the natural organization of these parks. Once you sketch out an itinerary, the information you want is grouped together and the information you don't need is elsewhere.
Despite these strengths, I find the organization of the book a little odd and I found that it took a while to get used to using it effectively. For example, the last three chapters are on Greater Yellowstone History, Geology, and Ecosystem. You might think that this information belongs earlier in the book as part of your orientation to the area. The book has a nice collection of maps, but they are in a weird location in the middle of the book that forces you to flip back and forth to use them as trip planners for hotels, activities, and hiking trails. These might go more naturally at the very front or back of the book. There are some nice full-color pictures scattered throughout the book (mostly in the front), but none of them go with the text that surrounds them.