"And I disagree that you have to have read and or used all the recipes in it. Even if I only like or use just one recipe in the book, that alone makes it good."
I think, maybe I didn't explain myself clearly. It is for exactly the reason above, that I feel a simple yes/no with a comment, is more valuable to a prospective reader, than a scaled rating system.
A comparative scale, would suggest that you have compared the two, or many books objectively and wholly, whareas,
"Recommend: Found a great recipe for a rub, that is fantastic- pg 35"
would be a fairer representation of the voters overall impression of the book and his/her investment in the book itself.
Just my Opinion.