The book's content is great. Brendan Howlin obviously knows what he's talking about, and he's passionate about it. However, his writing could have used some touching up. He writes in run-on sentences, which I wouldn't have a problem with if his editors had punctuated them correctly with a semicolon instead of a stream of commas.
There is one point where Brendan says in December at the winter solstice, the earth is at its farthest from the sun. This is a woefully common misconception, but I was frustrated to see it in this book. The earth is in fact closest to the sun in December, and its seasons come from its axial tilt, not closeness to the sun. Otherwise, why would there be opposite seasons down south of the equator?
That aside, I am glad I bought and read this book. It has a lot of really good information for the beginning Druid or the non-Druid, and despite the writing style I would still recommend this book.