On the CNN side, my biggest complaint was the mics were not indeed cut at the end of each persons time. If I was undecided, I wouldn't want to listen to two old men bicker, I'd want to actually hear their opinions and viewpoints.
They let it slip to some back and forth with both mics active at the same time on occasion. If they can't manage that, then they shouldn't get to host any presidential debates in the future. Luckily the next and last debate for this election is not them; we'll see how ABC does.