Many book reviews will critique the book and the author, although most book reviews are generally favorable towards the author. There are a few that are panned, but this is not like a movie review where a movie is panned by critics but still rakes in money at the box office. A negative book review can be devastating for an author but more importantly, for a publisher. For this reason, book reviews do not pan a book as they might a movie. The exception is when a book is written by a well known writer that does not live up to previous works.
Anyone who wants to sell their writing should seek out book reviews for this purpose. If the author knows a book reviewer, this can be easy. More often than not, the writers who write these notices are not known to the authors. While major publishing houses can easily get book reviews about new works, it can be difficult for the self published author to do the same. A self published author has to try to get self published book reviews for their novel through self published book marketing.
A good book review should discuss the merits of the book, give a basic outline as to what the book is about and talk about the characters and writing style. It should not give away the entire plot, or the twists and turns, if any. This is for the reader to discover. Good book reviewers can be found working freelance as well as for major magazines and newspapers. Most people do not pay attention to the name of the reviewers, but do read the notices. If the book reviews seem encouraging and of interest to the readers, they are more inclined to buy the work. For this reason, it is in the best interest of any author to get as many book reviews published of their work as possible. Readers look for book reviews to tell them if the book is worth reading. If they feel that it is, they will then buy the book.
Book reviews help marketing
Book reviews are an essential part of marketing. In fact, they are so important that most publishers will send works out for book reviews before printing up the dust jacket so that the notices can be displayed on the covers. Book reviews give readers a look into the work so that they can see if it is something that they will enjoy reading. These notices are not sales pitches, but a review of the plot, the writing style and the characterization in the book. They should not give away the secrets of the work. They are used to tell prospective readers a bit about the book so that readers can make up their minds whether or not they want to buy the work.