I visit state parks a lot, and this is the first book I've seen with all the information I'm looking for.
The trail maps and mileage tables are great - I can go for a quick hike after work without having to find a map behind the park office desk. I like the campground maps as well. They have desriptions of all the prime camping spots and recommendations for both wilderness campgrounds and family oriented sites.
I also do a lot of obscure sports like butterfly watching and cross-country skiing, and the guidebook covers those activities, plus rock climbing, birding, and horseback riding (it also has the mainstream activities like picnicking and swimming).
The book covers about 80 or so wildlife areas in New Jersey, and it's been a great help for the ones I've visited so far. I would recommend this book to anyone living in or near New Jersey who likes the outdoors.