Yelp! gets some negative press. I have a handful of customers that rail against Yelp!'s business plan of driving down non-active users at the expense of individual reviews. The problem is that Yelp! hides the reviews of users who are not active, which is prejudice against businesses that are outside of Yelp! target market, namely restaurants.
The issue with Yelp! is that the reviewers are the products and advertisements that Yelp! sells to the advertising businesses for a fee. If your business has many, hundreds of 5-star reviews from 1-time users, in other words, non-habitual Yelp! users, Yelp will collectively 'hide' all of those reviews and their counts in favor of their habitual reviewers. My gadget repair shop has hundreds of positive 5-star reviews, but Yelp! only shows less than 70 5-star reviews. Also, it promotes the 1 or two 1-star reviews, as a means to pressure the shop to advertise for better placement.