He is not doing terrible. He held is own. That is good enough for this first debate.
He is missing key points. For example, when asked what he would do to fight ISIS, he should have said "The first thing we need to do to stop ISIS is stop letting them into our country. Secretary Clinton's plan to bring more people from Syria is national suicide as seen in the countries of Europe."
On cyber security Trump should have hammered Hillary for her private server and mishandling of classified. What the heck. The again he wont look as aggressive and insulting as she is. This woman is vile throwing trolling epithets at Teump like that and then her fake smile when he tells how her campaign was vicious on Obama