I think some of the reviewers' comments below are probably correct but none of them are serious drawbacks. True, the maps in this guide are not EXTREMELY detailed, but if you want a really detailed topographical map, you can always get one. The actual trail descriptions in this book are painstakingly detailed -- it even gets tedious. So if you can't find every tree along your route marked on the maps here, just use your imagination a little and wing it.
"Walking in Spain" describes thirty or so of the best trails in Spain, highlighting trails in Mallorca, the Alpujarras Mountains of Andalusia, the area around Valencia, Castile's Sierra de Gredos and Sierra de Guadarrama, the Spanish Pyrenees, Galicia, and the Cordillera Cantábrica. Hikes vary from longer hauls like the 23-day Pyrenean traverse and the month-long Camino de Santiago to shorter 5- and 6-day hikes and walks you can do in less than a day.
I've used the guide to get some great ideas for an upcoming hiking trip to the Alpujarras Mountains and the Sierra Nevada and have found it extremely useful. It lists numerous places to stay, ranging from 30- and 40-euro "pensiones" to dirt-cheap hikers' "albergues". You're not going to find a list of every single cheap place to crash your head here (if you did, you would have a book twice as big as this one), but you won't find yourself stranded. There's also a bunch of affordable eating places listed in this book.
A plus for hikers who want to tackle all or part of the famous St. James pilgrimage route is that the guide's recommended day-to-day itinerary drops you off at the end of each day in towns where you can get food and water. A chart also shows the distance between each official "albergue" and the next.
This book comes up a little short on cultural information, but you can always take a look at Lonely Planet's general guide to Spain. Recommended. Five stars.