I normally use the Rough Guide series of books, but gave Lonely Planet a try.
I guess one gets used to the structure of a preferred guide, so I was pleasantly surprised at how immediately readable I found this book. Clearly a lot of thought has been given to the likely needs of a typical reader and the layout designed to suit.
I liked: the 25 Top Experiences section - which was not a list of museums and cathedrals, but included Pintxos in San Sebastian & Flamenco in Andalucia (bth of which are personal highlights of my trips); and the What' New section with updates since the previous edition.
The Eat Like a Local 8 page section was very good, and practical. As an example it explained that you should ask for vino de Manzanilla, not just Manzanilla. I can personally confirm that if you ask for the latter you will get chamomile tea! I thought it was my pronunciation.
I also liked the Tips Boxes presented throughout. So typical tips would be: Don't visit the Alambra and Seville Cathedral on the same day - too much to take in; and how you can reserve (cathedral) tickets online to avoid queues.
The Understand Spain section was excellent, and included sections on Spain Today, History, Bull Fighting etc.
I found the maps very clear, including a fold out Barcelona map, and there is a reasonable number of photographs throughout. It is not a photo guide type book, and I was happy with the balance of mostly text.
In summary I was very impressed with this book. It is excellent for both pre-visit reading, and as a traveling companion. Recommended. Looking through the section covering the regions I have visited, the guide gives the feel and details that mirror my experiences.