This National Geographic product functions well as a short, concise overview of the National Parks in the United States. (That is not to say that the book is short, just that the individual reviews on each park are short.) Each park gets a map, some beautiful color pictures, and a several pages of description. You find out good times to visit, places to stay, and sights to see. Also included are nearby attractions that you can also visit when you are in the area. The book is well put together, has great photos, and just feels like a high quality product.
Now so you won't be disappointed, let me note what it isn't. It isn't a book covering the entire park system. It doesn't cover monuments, forests, or other national park attractions other than the NATIONAL PARKS themselves. It isn't all inclusive on each park. If you want to know all of the trails, a complete list of attractions for each park, or other specifics to each park, you should buy park specific books. They are on Amazon and you can easily find one for whatever you need.
But this book does get you started if you are trying to decide what parks to visit or if you just want a very nice book to summarize all of the great National Parks.