Worthless, hence the price. It's just a list of tables based on habitat. It's the sort of thing you can cobble together in 5 minutes, and yours would be customised for your own campaign, not completely random.
I'm one of those people that really likes random encounter tables. They keep me from using the same monsters over and over. If you like them too than you will like this book. I have found it very usefull in my Mutant Future games.