The review of a book needn't be complicated. This isn't your high school or college English class. A succinct few sentences of your opinion and why you loved or hated the book plus your star rating is enough.
Here's one of my favorites from the new novel, Piper's Passion:
"Again Ms. Carver's new novel, Piper's Passion, brings excitement to the three challenging situations that run through the book. From the first page to the last the story keeps one's interest and never "sinks" in the middle. Ms. Carver's knowledge of a missionary pilot in the Brazilian Bush adds many exciting moments to the story."
Write more if you wish, but it doesn't have to be a huge undertaking. Fortunately, I've never had a review which gave away the ending or any well-guarded plot point. Book Fun reviewers are super!
Blessings on you all,