1. The two candidates are in some ways representative personifications of their parties. Matt Grossmann and I have a post up at the Monkey Cage today looking at the debate through the lens of Asymmetric Politics. Like a typical Democrat, Clinton emphasized specific policies, while Donald Trump's preference for broader rhetorical themes fell in line with the pattern of previous Republican candidates.
2. It is important to undergo thorough pre-debate preparation and practice in order to deliver a performance that will be judged satisfactory by the news media. The rules—both official and unofficial—of these events give a decisive advantage to candidates who have memorized pointed and pithy responses to likely topics and questions, who strategically seek to draw their opponents into discussions of unfavorable subjects, and who project an image of good-humored unflappability throughout. This was the lesson of the first Obama-Romney debate in 2012, and it was reinforced again last night. Unlike Clinton, Trump exhibited no sign of having prepared for the debate in any systematic way, which affected the crispness and intelligibility of his own responses as well as his ability to defend himself and counterattack in exchanges with Clinton.
3. With that said, it is worth considering more explicitly how much the debates should properly influence voters' impressions of the candidates. If the difference between a "good" and "bad" performance is primarily a function of how disciplined a candidate is in subjecting him- or herself to the generally annoying task of debate prep, rather than an indicator of substantive command of policy, personal character, or other attributes, are we judging debate participants on grounds that have much to do with their actual responsibilities in office?
4. For the past several weeks, there has been something of an offensive among Democrats, especially noticeable on Twitter, against the prevailing media coverage of the campaign. Democratic complaints have included what they view as insufficient coverage of dishonest behavior by Trump, ineffective or absent media "fact-checking" of Trump's public claims, and excessive media preoccupation with Clinton's email practices and the activity of the Clinton Foundation. These critiques reached a peak after the September 7 candidate forum hosted by Matt Lauer, who was accused by Democrats of being tougher on Clinton than Trump, and evolved into an open discussion over the past several days about whether it would be proper for a debate moderator to challenge or correct factual misstatements by candidates. (Not irrelevant to the partisan dimension of this subject is moderator Candy Crowley's decision to "fact-check" Mitt Romney's claims about Benghazi in the 2012 town hall debate, which Democrats and Republicans alike commonly view in retrospect as a turning point in the election.)
It seems likely that these complaints, whether they represent sincere advocacy of media responsibility, cynical working of the referees, or a bit of both, had some effect on Lester Holt's performance last night. Holt moderated with a light touch, but he did explicitly dispute Trump's claim of consistent opposition to the Iraq War, and his line of questioning included a few tough personal challenges of Trump (most notably on the subject of "birtherism" and Trump's claim that Clinton lacked a "presidential look"). When combined with recent media coverage that devotes more attention to examples of Trump's dishonesty, it's hard to escape the conclusion that Democrats have partially succeeded in convincing journalists on this point.