WordPress comes with a pretty simple comment management system that should be good enough for small sites. If your site gets a decent amount of comments on a daily basis, you may want to upgrade to more advanced comment systems or use plugins like Comments Like Dislike to let your readers rate comments.
This plugin displays comment like and dislike buttons. It can display them before or after comments. You have the option to display likes, dislikes or both. Webmasters have the option to change like and dislike icons in the back-end.