WP Customer Reviews plugin is one of my favorite plugins. It belongs between the only testimonial/review plugins, which allows you to setup a specific page on your blog to receive customer testimonials for your business/service OR to write reviews about a product. You can either approve the review or trash it from the wordpress dashboard. All submissions are moderated, which means that you choose which reviews get shown.

After upgrading to the newest version 3.0.1 I came across a message: You did not pass our human detection check. Code 6,20.

The reason for this message was a “very short review” itself.
I filled out all the required fields and typed “test” in the textbox, clicked on “Check this box to confirm you are human” and boom! The message came up. Then I rewrote the message in the textbox and made it longer, maybe couple of sentences and clicked on the human checkbox and it worked perfectly! Just an FYI: You might get a similar message if you trying to copy and paste reviews.
This issue should be fixed in upcoming 3.0.2 version.