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.