The antonyms of "rating highly" can be described as unfavorable, unimportant, or insignificant. Some words that describe unfavorable ratings are disapprove, condemn, criticize, denounce, and reject. For those who view something as unimportant or insignificant, words such as trivial, unremarkable, and minor can be used. It's important to remember that everyone has their own subjective opinions and preferences, and what one person may consider highly rated can be unimportant or unfavorable to another. Therefore, it's essential to look at both sides of the spectrum when it comes to rating something.