All user reviews on the site can be rated. At the bottom of each review, it will include the question "Was the above review helpful?" and Yes or No buttons where registered IMDb users can cast their vote.
Please note that "helpful" doesn't necessarily imply the review was "positive" or "favorable". A review can be helpful even if it rips the film to shreds, because it can help readers decide not to waste their time or money watching it.
Likewise, to find a review helpful doesn't mean that you agree with it. A well-thought analysis of a film can still be helpful and shape your opinion differently or bring a novel point of view to light, even if you ultimately disagree with the reviewer's conclusions.
The aim of this feature is to help valid, well-written reviews surface at the expense of less interesting ones. We think that our users are ultimately in the best position to decide what's good or not for them, and that their opinion should be given consideration when displaying user reviews on the site. If a review with which you disagree is rated as more helpful, this means a majority of users had a positive opinion of the review, and not necessarily the film.