The claim of the title is a bit far-fetched but it can still be a good resource.
Written for those based in the United States, it certainly does try and take you through the whole A to Z of starting a business. It cannot be everything to everyone but it has a reasonable stab at covering all of the bases and, if nothing else, acts as a great jumping-off point to other reading and research. For those who are not based in the United States, there will be a lot of irrelevant information you will need to skip over, it could not be worthwhile for you.