Even though this book is older (1970s) it is still pretty valuable. Like other tomes during this time period, it is pretty heavy in its description in order to make it easier for others to copy.
That said, this book really is a starting point. Some of the ideas are not very applicable to now, due to advances in technology and understanding, such as geothermal energy and improvements in solar energy.
I did like how the authors were honest about some of the downfalls of what they built. They don't go much in how to correct them, but it is something that can be researched. For example, they had a problem with flies in the rabbit area, and they brought in chickens to dig around and eat the fly larva in the droppings. I think that problem might be fixed with better screening instead.
Overall, it is a good book and I like how it focuses on making one more self sufficient in an urban setting, which is where most people live. It's not realistic for everyone to give up their jobs and move to the country.