Google has recently started integrating merchant ratings, aggregated for Google Product Search, into your Ads if you meet a couple requirements. Those requirements include at least a 4 star rating and a minimum of 30 reviews.
There are certainly advantages for having this Google feature in your PPC Ads. For one, the rating builds trust with the consumer which could lead to higher CTR (Click Through Rate) percentages. This feature also allows your Ads to stand out and become more visible, even against higher ranked Adcopy, because the Ad gains an increase in size when the star rating is present. But this is relative to the rating of the other advertising being shown. One of the great features about this is how these ads are charged to your account, merchants are only charged if “someone clicks on the headline of your ad - clicks on the review link are free.”
Currently, ads will not see this distinction on all searches. I ran several of the same searches and it looks like Google is simply A/B testing this feature at this time or it may be something they intend to only show when certain special criterion are met. Google states, “These star ratings, aggregated from review sites all around the web, allow people to find merchants that are highly recommended by online shoppers like them.” In any case, it is a welcomed addition to those merchants that have a good Google Product Search rating.