My wife and I just completed a tour of some of the major cities of Spain. Before we went, we purchased this Lonely Planet rather than the individual city guides. Since we were part of a tour and merely wanted some supplemental information, we purchased this one.
The information they give on each of the sites and monuments is helpful. Although it didn't go into intense detail, you did get enough background historical information to make some sense. This book also gave us some good ideas of sites to see which the tour we took did not tell us about.
Some of the information is a little inaccurate, don't take this information as 100 percent correct. For instance, admission to the Capilla Real is 350 ptas and not 300. The hours were a little off also. We did find the maps to be pretty accurate. The walking tour of Madrid was a little more difficult to follow, but it could be done.
A fellow traveler had the Let's Go book for Spain and Portugal. Consistently, we found her looking at our Lonely Planet for better information.
I would recommend this book for a trip to Spain. Remember that it is supplemental and should not be taking as 100 percent accurate.