I have been writing business plans for a quarter of a Century, both as an executive and as an adviser. Lately I found myself working on three simultaneously, for wildly diverse businesses. This book really helped. Unlike many sources, it did not thrust a template at me (though a couple are included as examples). It did not regurgitate standard textbook answers from international "experts". What I found helpful was the distillation of stuff I knew and loads I had forgotten into a logical and easy to read process. Whether or not you've written one before, BBP will help you write a better plan.
It's a good book to grasp the very basic principles behind a business plan. Provided mere pointers for structure which is ok in general. Ultimtely this is a quick reference book only providing springboards, it will not help you come up the business idea - this is the part you need to do! This little book will help you get your business idea written down providing examples and ideas in what should be thought of as part of the plan.
Overall a quick and simple read. Nothing groundbreaking. A good reference starter.