He continues to improve, but it’s from such a low starting point. He kept it together for much longer than in the first debate, lost his composure for a while, and then re-gained it before having a bad last half-hour. He showed some preparation especially on the Supreme Court at the beginning (referring, for instance, to a “well-crafted decision”) and made much more of an effort to get in his hits against Hillary even if not directly relevant to the question.
But he had a hard time defending all his personal and professional baggage–a couple of times he blamed Hillary for not doing more to make it impossible for him to use Chinese steel and to force him to owe federal income taxes; he got shouty, interrupted Hillary with his trademark “wrong!” interjection, and muttered that she is “such a nasty woman”; and he refused to commit to accepting the result of the election. It is the last that is already driving the post-debate commentary and surely won’t play well.
The problem for Trump is that maintaining discipline is so foreign to him he simply can’t turn in a complete debate performance. If he loses on November 8, these three debates will be a big reason why.