The purpose of a book review is to inform other potential readers/buyers about the book. Feedback is also helpful to the author: A good review can help increase sales; a poor review can have the opposite effect.
To post a review on Amazon, you have to be an Amazon customer. Goodreads and other platforms (Barnes & Noble, Chapters/Indigo) allow anyone to post a review.
How many stars?
The number of stars you choose is pretty arbitrary. I personally hate rating things on a number scale. But, every reviewer has their own preferences and agenda which will guide their choice.
A five-star review should be for a book that has everything: good writing, good editing, and a story that makes you want to read it again and tell your friends about. Some people are too generous, which is generally not a bad trait to have in life. But I’ve looked at all the reviews of some reviewers to find that they’ve given a five-star review to all 30 books they’ve read. And while it’s very polite, it doesn’t serve the purpose for potential new readers. Seriously, nobody could be that lucky.
Explain your star rating.
Keep it short, keep it simple. It’s not an essay; it’s not a book report; it simply consists of a few (thoughtfully constructed!) sentences—a paragraph.
It should go without saying but … read the book. At least, give it a fair shot and explain why you couldn’t get through it if you didn’t. If you haven’t read it, don’t review it. If you’re not able to download it, or the printer screwed up and some of the pages are upside-down, that’s not the author’s fault—take it up with technical support or the print-on-demand service you purchased it from.
Although the reader can refer to the synopsis on the sales page or the back cover of the book, include something about the story. Don’t share any major reveals or spoilers, and don’t just copy what the author (or another reviewer) has posted. Provide context for your comments.
Did you like the book? Would you recommend it? Why or why not? To whom?
Give specific examples. For fiction—discuss the character development, use of setting, pacing, etc. If it’s nonfiction, discuss the organization, ability to get across the point and passion for the subject.
Add your personal insights—how the book related to you, affected you, etc. Don’t go on and on about yourself, don’t disrespect the writer. Find something nice to say and be gentle with your suggestions for improvement. Your review is about the writing, not about the writer.
If you received a free copy of the book (or got paid!) in exchange for your review—be transparent about it. This should not be happening on Amazon … but it does. (More about the 5-star-review “marketing strategy” in an upcoming post.)
Only a small percentage of readers review books. Support your fellow author, and help out your fellow readers, by taking the time to tell others about those books that stand out … and about those not worth the price.