Product Listing Ads are a fairly new thing, even though the Shopping Ads system they evolved from has been around for a while, but Google is already making new features available for these type of ads. Product ratings extensions can now be used with PLAs, the use of which has shown to boost the all mighty click-through rate.
This is important because although Google doesn’t list a Quality Score for PLAs, there must be a system in place to determine which ads are shown and which are not. Just because Google doesn’t list a score that you can easily monitor doesn’t mean they’re not ranking product listings in some way, and you can be sure that CTR is a big part of it. Since you can bet that your competitors are using these extensions, it’s a good idea to start using them or some sort of extension as well. (We noted in our guide to standard ads that any extension is better than none, if nothing else because of the increase in space the ad takes up. You may want to be trim and svelte, but you want your ads to be plus-sized.)
Google is giving merchants until October of this year to start providing their review data, either directly or a through a third party. In the mean time, you can still use the extension since ratings are aggregated through a variety of sources, but after the cut off date, you’ll be, well, cut off. Google has noted that there’s likely to be a stampede of people trying to get this feature added, so don’t scream at them if the process takes a bit of time. (I may have paraphrased that last bit.)