There are many different styles in writing book reviews. A pre-requirement is to read published reviews written by acknowledged critics. At a very broad level reviews may be classified as those written to highlight the book in question and as those written to highlight the knowledge of the reviewer. Either is acceptable. The better critics are well-read and knowledgeable. However, it is well to remember that while criticism may look easier than construction, the better read and knowledgeable the critic, the easier it looks. As always with writing, book reviews also require proofreading and editing.