Other users can upvote or downvote product reviews.
To enable this feature, you must go to the tab Voting/Review settings and enable the option “Show vote section”.
Moreover, by enabling the option “Show review notes”, you can show how many upvotes the review has been given out of the total number of votes.
By default, only registered users can vote another review. If you want to extend this capability to any user, enable the option “Enable vote for all”.