This book is an excellent description of the grammar of Classical Japanese. However, despite the claim that it is "free of linguistic jargon" (why does every grammar seem to have that on the back), Vovin is a historical linguist, and the book is actually full of jargon. While it's not so dense as to be incomprehensible, for someone without a background in linguistics, it could be slow going. It also gives an analysis of the morphology that is very different from the traditional analysis. If you want an accurate, well laid out, well presented, carefully explained, and well-sourced and evidenced linguistic description of Classical Japanese Prose, this is the book for you.
If you want to study Classical Japanese, you should not start here. Instead, come to this after you've had some Classical Japanese already and are at least comfortable with the traditional description (that means know terms like mizenkei, renyoukei, shuushikei, rentaikei, izenkei, meireikei, jodoushi,upper bi-grade, lower mono-grade, etc), and your understanding will be much enriched.
The only qualification I would make is that Vovin makes some rather strange (in my mind) claims about pronunciation that I would really like to see stronger motivation for, such as word final implosives and word-final voiced velar nasals in loanwords, and I would have liked at least a cursory discussion of accent, rather than being referred to another expensive, difficult to obtain academic work...but these are minor things, I am nitpicking at this point.
Really, if you are interested in Classical Japanese and can get this book, you should, although you probably shouldn't read it until you have a bit of background in the language, if you want to use it as a self-teaching tool. That said, if you want to know about Classical Japanese, rather than be able to read it, then this is THE book. Shame about the high price.