Peoeple don't like Donald Trump as a person because they he is clearly narcissistic (though not necessarily clinically), and there is good reason to believe that he is a sexual predator (a tape of him describing an instance of sexual assault, and 15 accusers). He lies constantly, is extremely petty, and spends far too much time associating with racists and other terrible people.
They even dislike him as a politician because almost everything he wants is bad. A wall is a total waste of time when they don't even know whether it would be worth the expense (because it's arguable just how many illegal immigrants sneak across the Mexico-American border). We don't have the numbers to really know whether it'd work, but from what we do have it doesn't seem like it'd be worth the money (when >40% of illegal immigrants come here legally and overstay visas).
Peoeple say that He backs horrible bills, like the current GOP tax bill and his own health care bill. The health care bill, if passed, would literally lead to people dying for absolutely no good reason. The GOP tax bill hurts education by treating grad students' teaching waivers as taxable income. (It trades time spent teaching for tuition)
Yeah i think they are actually right for somethings