Muhammad the Greatest: A comparative study

It is from my humble studies that after analyzing the sunnah (legal ways of the prophet Muhammad) that I've come to realize that islam views the example of character we find in the sunnah to be the one of the best examples of character for people to follow.

But I've also come to learn that not only do many people disagree and say that he is not the best example of character but say that he is one of the worst, if not the worst example of character. So my simple question is why do people see Muhammad in such a negative way? Is Muhammad the best example of character? Let's have a dialogue