I don't know if the Virginia Quarterly Review blog post Does Every Book Deserve A Review? answers the question it raises in its title. So I will. Or I'll sort of answer it.
Certain books "deserve" a review whether or not they meet someone's standard for goodness, so to speak. They do not have to be wonderful to deserve a review. They deserve to be reviewed even if they can't be highly recommended.
1. Because the authors have a distinguished body of work. Even if they've written something that isn't up to their usual standards, their books should be of interest to the reading public--especially, if, say, the book is a miss because the authors were trying something new. The effort is worthy of being part of the literary discussion. Books written by people like M.T. Anderson, Neil Gaiman, and Lynne Rae Perkins deserve a review.
2. Because the authors have written books in the past that have had some kind of impact on popular culture. Whatever anyone thinks of Stephanie Meyer as a writer, her books have had a big impact on the reading public. Her next few books deserve a review.
3. Because the subject matter is significant in some way. This could mean being significant in a narrow field, even if not significant to the general public. Nature magazines will review significant environmental books, for instance, that general review publications might not. Same for history magazines, food magazines, and on and on.
4. Because the authors have tried to do something different--breaking out of a genre, breaking away from a fad, etc. For instance, somebody, sometime, somewhere is going to write the book that starts to lead readers away from rich-girl-gone-bad stories. That book deserves to be reviewed!
All these kinds of books deserve to be reviewed. Or perhaps a better way of putting it would be that they deserve to be discussed.