Six or more stars, really.
I finally bought this book after "thinking about it" forever. (I have a problem with the thinking thing.) Well, just as has been said before... drop everything else and go through these books. You'll be WAY ahead if you do. I studied classical guitar for a year in college (though I'm primarily a jazz-rock-etc. player), and this SHOULD have been the book they used back then. The exercises are melodic enough that anyone with an ear should be able to follow them with little difficulty, and still you'll learn everything you need to learn.
The progression of exercises is sensible, and everything holds together as a meaningful whole, an attribute lacking in most guitar instruction books. (Though you may want to add Arnie Berle's "New Guitar Techniques for Sight Reading" as well. Not that there's a gap in Leavitt's books, just that Berle's approach may broaden your approach a bit. Berle's other books are good as well, in my opinion.)
So don't think (as I did) that this is a method for "that kind of player over there, but not me," as I did. Regardless of your intended style, what you will get here will put you years ahead if you just do it. After that, you'll be ready to tackle anything - it'll still be work, it always will be, but you won't spin your wheels as hundreds of thousands of players do.
Guitar players owe something good to Leavitt for this book, really. It's obviously the product of a sensible, disciplined, knowledgable and concerned mind.