I think he will do well in a debate, her public speaking skills suck and the only way she wins is if CNN feeds her the questions a week out.
Almost forgot to write a response along with my disagree!
Trump is many things, but when he's not up in front of the hometown crowd with Jock Jams vol. 3 blaring, he has yet to show himself to be a good orator. He seems to have his verbal "safe space" that he retreats to when pressed, which demonstrates to me that his mental agility is not the greatest. He can talk about his business success and how cool America is, but if you press him for specifics he just goes back to his previous talking points. One thing he does really well is avoiding the impression that he's getting flustered. His demeanor is calm even when his mind is struggling for a succinct and definite answer. I suppose you could say that he hides his fluster with bluster. That particular quality is on full display in the recent interview he gave to 60 Minutes along with Mike Pence. You can watch the full interview
here, but if you value your time you can just watch the greatest (worst?) hits of the interview
here
Keep in mind, however, that lacking an agile mind is not always a bad thing; GWB was not the most articulate debater, but he had an unmistakable charisma and presence that were considerably at odds with Gore in the 2000 election, and again with John Kerry in 2004. Though he wasn't always the most erudite, Bush managed to hold his own and then bolster his image away from the debate stage. We'll see if Trump can boost his image any further in the public eye or if he's already blown his load.
As for Hillary, she has all the charisma of a wet dishrag but has such a keen grasp of the issues and practiced debate style that I think the betting odds are heavily in her favor. She was good against Obama in 2008, and pretty good against Bernie this time around. I say only "pretty good" because the democratic debates were pretty saccharine affairs this year, especially after O'Malley left. Who knows? Perhaps she'll fall flat. Perhaps Trump will take his debate prep seriously and put on a great performance. Either way, I'm going to clear out my schedule during those time slots and prepare to drink the pain away.