Obviously killing the crazy king was a good thing overall. Since Jaime is the Kingslayer he gets the blame for everyone else who died as well, so even though Clegane and Amory were the ones killing innocent children and raping women (in Clegane's case), Jaime is seen as complicit in those crimes as well.

Also, Jaime is a complete ass who shows no compassion. He almost gleefully pushes a 7-yr-old out of a tower. No wonder people hate him. And let's not forget the incest.