Someone with little technical
knowledge who gives a review of a product or service would say this phrase.
They would feel as if they are handing out good advice to
people; But in
reality they dont have the experience or analytical ability to give a detailed review.
John: "How is your
new camera?"
Bill: "it does exactly what it says on the tin"
John has no idea whether the camera is good or not. He just knows that it takes photos.
If Bill had more technical
knowledge, he would have given more useful
information.