Having a background image that relates to the review text will lead to a higher conversion rate than having a review with a background color. Having an image relating to the service that the reviewer used provides a visual companion to the review provided. It gives the customer a visual aid, enabling them to connect the review with a service they can see which could be the final piece of the jigsaw that they need to contact the business for help.
From our A/B test, the homepage with a background review image converted at a higher rate than the review with a background color. However, the difference is not too large between the two (just under 2% difference).
As the difference in results isn't too significant, we are going to run more experiments on this to get a more concrete, conclusive result.