★☆☆☆☆ I didn't care for it, and won't be returning to it.
★★☆☆☆ I didn't mind it, but don't care to read it again.
★★★☆☆ I like it, and would likely read it again.
★★★★☆ I enjoyed it, would read it again, and would recommend it.
★★★★★ It defied my expectations and is now one of my favorites. Highly recommended.
As I give my personal rating on other things such as board games and movies, you can expect those ratings to follow this pattern.