What’s unique about WP Customer Reviews is its ability to tell search engines whether your page contains users’ or your own review. It achieves this by showing the respective schema microformat to Google and alike.
Still, you have the freedom to change the design of the review and show the admin responses in a separate field.
Furthermore, it’s lightweight and supports custom themes. Your page loading speed won’t be affected since it works well with caching plugins, as well.
There are also enough anti-spam measures to prevent your site from getting bombarded by harmful reviews.
It’s a pretty good deal, considering you don’t have to pay anything to install WP Customer Review.