Backpacking Pennsylvania does exactly the job the title leads you to believe it will do. 37 major trails are described and made accessible to the the Pennsylvania Backpacker.
Each trail narrative is preceded by a chart summarizing 13 "want-to-know" items for the trail: its length, approximate time needed for the trip, a difficulty rating, typical terrain and trail conditions, blazes, water supply, area vegetation, trail highlights, maintaining organizations, sources of maps/guides/contact information, and trailhead directions.
The trails are divided into seven geographical regions, with a map for each region showing the counties and general layouts and locations of the trails there. For each of the 37 trails, another map shows the local roads, towns, creeks, parks, and potential campsites and vistas. The narratives are sufficiently detailed that backpacker armed with this book would be able to save the purchase of many individual trail guides and maps, though these would offer more in-depth information on the history, geology, or other particulars.
This book is a great guide for planning backpacking ventures of appropirate duration, difficulty, and location in the Keystone state. I most recently backpacked the Bucktail Path and found Jeff's summary to be quite on-target. It should be in every Pennsylvania backpacker's library.